- 30 4月, 2013 10 次提交
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由 Jiang Liu 提交于
Use common help functions to free reserved pages. Signed-off-by: NJiang Liu <jiang.liu@huawei.com> Cc: Yoshinori Sato <ysato@users.sourceforge.jp> Signed-off-by: NAndrew Morton <akpm@linux-foundation.org> Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>
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由 Jiang Liu 提交于
Use common help functions to free reserved pages. Signed-off-by: NJiang Liu <jiang.liu@huawei.com> Cc: David Howells <dhowells@redhat.com> Signed-off-by: NAndrew Morton <akpm@linux-foundation.org> Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>
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由 Jiang Liu 提交于
Use common help functions to free reserved pages. Also include <asm/sections.h> to avoid local declaration. Signed-off-by: NJiang Liu <jiang.liu@huawei.com> Cc: Mikael Starvik <starvik@axis.com> Signed-off-by: NAndrew Morton <akpm@linux-foundation.org> Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>
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由 Jiang Liu 提交于
Use common help functions to free reserved pages. Signed-off-by: NJiang Liu <jiang.liu@huawei.com> Cc: Mark Salter <msalter@redhat.com> Cc: Aurelien Jacquiot <a-jacquiot@ti.com> Signed-off-by: NAndrew Morton <akpm@linux-foundation.org> Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>
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由 Jiang Liu 提交于
Use common help functions to free reserved pages. Signed-off-by: NJiang Liu <jiang.liu@huawei.com> Cc: Mike Frysinger <vapier@gentoo.org> Signed-off-by: NAndrew Morton <akpm@linux-foundation.org> Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>
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由 Jiang Liu 提交于
Use common help functions to free reserved pages. Signed-off-by: NJiang Liu <jiang.liu@huawei.com> Acked-by: NHans-Christian Egtvedt <egtvedt@samfundet.no> Cc: Haavard Skinnemoen <hskinnemoen@gmail.com> Signed-off-by: NAndrew Morton <akpm@linux-foundation.org> Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>
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由 Jiang Liu 提交于
Use common help functions to free reserved pages. Signed-off-by: NJiang Liu <jiang.liu@huawei.com> Cc: Russell King <linux@arm.linux.org.uk> Cc: Catalin Marinas <catalin.marinas@arm.com> Cc: Will Deacon <will.deacon@arm.com> Signed-off-by: NAndrew Morton <akpm@linux-foundation.org> Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>
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由 Jiang Liu 提交于
Use common help functions to free reserved pages. Also include <asm/sections.h> to avoid local declarations. Signed-off-by: NJiang Liu <jiang.liu@huawei.com> Cc: Richard Henderson <rth@twiddle.net> Cc: Ivan Kokshaysky <ink@jurassic.park.msu.ru> Cc: Matt Turner <mattst88@gmail.com> Signed-off-by: NAndrew Morton <akpm@linux-foundation.org> Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>
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由 David Rientjes 提交于
On large systems with a lot of memory, walking all RAM to determine page types may take a half second or even more. In non-blockable contexts, the page allocator will emit a page allocation failure warning unless __GFP_NOWARN is specified. In such contexts, irqs are typically disabled and such a lengthy delay may even result in NMI watchdog timeouts. To fix this, suppress the page walk in such contexts when printing the page allocation failure warning. Signed-off-by: NDavid Rientjes <rientjes@google.com> Cc: Mel Gorman <mgorman@suse.de> Acked-by: NMichal Hocko <mhocko@suse.cz> Cc: Dave Hansen <dave@linux.vnet.ibm.com> Signed-off-by: NAndrew Morton <akpm@linux-foundation.org> Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>
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由 Rob Landley 提交于
Generate asm-x86/cpufeature.h with posix-2008 commands instead of perl. Signed-off-by: NRob Landley <rob@landley.net> Cc: Thomas Gleixner <tglx@linutronix.de> Cc: Josh Boyer <jwboyer@redhat.com> Cc: "Paul E. McKenney" <paulmck@linux.vnet.ibm.com> Cc: David Howells <dhowell@redhat.com> Cc: Michal Marek <mmarek@suse.cz> Cc: Sam Ravnborg <sam@ravnborg.org> Signed-off-by: NAndrew Morton <akpm@linux-foundation.org> Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>
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- 26 4月, 2013 11 次提交
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由 Sebastian Ott 提交于
The pci config space accessors on s390 are (now) smart enough to figure out if a pci function is available. So instead of calling pci_create_root_bus and then pci_scan_single_device for each available function just call pci_scan_root_bus and let the pci core do the scanning (via config reads on all possible functions) and device creation. Reviewed-by: NGerald Schaefer <gerald.schaefer@de.ibm.com> Signed-off-by: NSebastian Ott <sebott@linux.vnet.ibm.com> Signed-off-by: NMartin Schwidefsky <schwidefsky@de.ibm.com>
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由 Heiko Carstens 提交于
We've seen repeatedly that 8KB stack size on 64 bit kernels is not sufficient. So simply remove the config option. Signed-off-by: NHeiko Carstens <heiko.carstens@de.ibm.com> Signed-off-by: NMartin Schwidefsky <schwidefsky@de.ibm.com>
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由 Martin Schwidefsky 提交于
Add a pointer to the system call table to the thread_info structure. The TIF_31BIT bit is set or cleared by SET_PERSONALITY exactly once for the lifetime of a process. With the pointer to the correct system call table in thread_info the system call code in entry64.S path can drop the check for TIF_31BIT which saves a couple of instructions. Signed-off-by: NMartin Schwidefsky <schwidefsky@de.ibm.com> -
由 Martin Schwidefsky 提交于
Store the stack pointers in the lowcore for the kernel stack, the async stack and the panic stack with the offset required for the first user. This avoids an unnecessary add instruction on the system call path. Signed-off-by: NMartin Schwidefsky <schwidefsky@de.ibm.com> -
由 John David Anglin 提交于
User applications running on SMP kernels have long suffered from instability and random segmentation faults. This patch improves the situation although there is more work to be done. One of the problems is the various routines in pgtable.h that update page table entries use different locking mechanisms, or no lock at all (set_pte_at). This change modifies the routines to all use the same lock pa_dbit_lock. This lock is used for dirty bit updates in the interruption code. The patch also purges the TLB entries associated with the PTE to ensure that inconsistent values are not used after the page table entry is updated. The UP and SMP code are now identical. The change also includes a minor update to the purge_tlb_entries function in cache.c to improve its efficiency. Signed-off-by: NJohn David Anglin <dave.anglin@bell.net> Cc: Helge Deller <deller@gmx.de> Signed-off-by: NHelge Deller <deller@gmx.de>
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由 Helge Deller 提交于
CONFIG_MLONGCALLS was introduced in commit ec758f98 to overcome linker issues when linking huge linux kernels, e.g. with many modules linked in. But in the kernel module loader there is no support yet for the new relocation types, which is why modules built with -mlong-calls can't be loaded. Furthermore, for modules long calls are not really necessary, since we already use stub sections which resolve long distance calls. So, let's just disable this compiler option when compiling kernel modules. Signed-off-by: NHelge Deller <deller@gmx.de>
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由 Will Deacon 提交于
When targetting 32-bit processors, __put_user emits a pair of stw instructions for the 8-byte case. If the type of __val is a pointer, the marshalling code casts it to the wider integer type of u64, resulting in the following compiler warnings: kernel/signal.c: In function 'copy_siginfo_to_user': kernel/signal.c:2752:11: warning: cast from pointer to integer of different size [-Wpointer-to-int-cast] kernel/signal.c:2752:11: warning: cast from pointer to integer of different size [-Wpointer-to-int-cast] [...] This patch fixes the warnings by removing the marshalling code and using the correct output modifiers in the __put_{user,kernel}_asm64 macros so that GCC will allocate the right registers without the need to extract the two words explicitly. Cc: Helge Deller <deller@gmx.de> Signed-off-by: NWill Deacon <will.deacon@arm.com> Signed-off-by: NHelge Deller <deller@gmx.de> -
由 John David Anglin 提交于
Change kunmap macro to static inline function to fix build error compiling drivers/base/dma-buf.c. Without the change, the following error can occur: CC drivers/base/dma-buf.o drivers/base/dma-buf.c: In function 'dma_buf_kunmap': drivers/base/dma-buf.c:427:46: error: macro "kunmap" passed 3 arguments, but takes just 1 I believe parisc is the only arch to implement kunmap using a macro. Signed-off-by: NJohn David Anglin <dave.anglin@bell.net> Cc: "James E.J. Bottomley" <jejb@parisc-linux.org> Cc: Helge Deller <deller@gmx.de> Signed-off-by: NHelge Deller <deller@gmx.de>
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由 John David Anglin 提交于
The Debian experimental linux source package (3.8.5-1) build fails with the following errors: ... MODPOST 2016 modules ERROR: "__ucmpdi2" [fs/btrfs/btrfs.ko] undefined! ERROR: "__ucmpdi2" [drivers/md/dm-verity.ko] undefined! The attached patch resolves this problem. It is based on the s390 implementation of ucmpdi2.c. Signed-off-by: NJohn David Anglin <dave.anglin@bell.net> Cc: "James E.J. Bottomley" <jejb@parisc-linux.org> Signed-off-by: NHelge Deller <deller@gmx.de>
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由 Arnd Bergmann 提交于
The Kconfig entry for USB_OMAP unconditionally selects USB_ISP1301, which is now only visible when USB_PHY is also enabled. This adds an appropriate dependency and enables USB_PHY in the omap1 defconfig, avoiding these build warnings: warning: (USB_OHCI_HCD && USB_OMAP) selects ISP1301_OMAP which has unmet direct dependencies (USB_SUPPORT && USB_PHY && I2C && ARCH_OMAP_OTG) Also fix a Makefile typo while we're at it. Signed-off-by: NArnd Bergmann <arnd@arndb.de> Cc: Felipe Balbi <balbi@ti.com> Signed-off-by: NGreg Kroah-Hartman <gregkh@linuxfoundation.org>
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由 Arnd Bergmann 提交于
The Kconfig entry for USB_LPC32XX unconditionally selects USB_ISP1301, which is now only visible when USB_PHY is also enabled. This adds an appropriate dependency and enables USB_PHY in the msm defconfig, avoiding these build errors: warning: (USB_LPC32XX) selects USB_ISP1301 which has unmet direct dependencies (USB_SUPPORT && USB_PHY && (USB || USB_GADGET) && I2C) drivers/built-in.o: In function `usb_hcd_nxp_probe': drivers/usb/host/ohci-nxp.c:224: undefined reference to `isp1301_get_client' drivers/built-in.o: In function `lpc32xx_udc_probe': drivers/usb/gadget/lpc32xx_udc.c:3071: undefined reference to `isp1301_get_client' Signed-off-by: NArnd Bergmann <arnd@arndb.de> Cc: Felipe Balbi <balbi@ti.com> Cc: Roland Stigge <stigge@antcom.de> Signed-off-by: NGreg Kroah-Hartman <gregkh@linuxfoundation.org>
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- 25 4月, 2013 1 次提交
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由 David S. Miller 提交于
Reported-by: NMeelis Roos <mroos@linux.ee> Signed-off-by: NDavid S. Miller <davem@davemloft.net>
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- 24 4月, 2013 2 次提交
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由 Josh Boyer 提交于
We need to check the runtime sys_table for the EFI version the firmware specifies instead of just checking for a NULL QueryVariableInfo. Older implementations of EFI don't have QueryVariableInfo but the runtime is a smaller structure, so the pointer to it may be pointing off into garbage. This is apparently the case with several Apple firmwares that support EFI 1.10, and the current check causes them to no longer boot. Fix based on a suggestion from Matthew Garrett. Signed-off-by: NJosh Boyer <jwboyer@redhat.com> Signed-off-by: NMatt Fleming <matt.fleming@intel.com>
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由 Borislav Petkov 提交于
Fix this: arch/x86/boot/compressed/eboot.c: In function ‘setup_efi_vars’: arch/x86/boot/compressed/eboot.c:269:2: warning: passing argument 1 of ‘efi_call_phys’ makes pointer from integer without a cast [enabled by default] In file included from arch/x86/boot/compressed/eboot.c:12:0: /w/kernel/linux/arch/x86/include/asm/efi.h:8:33: note: expected ‘void *’ but argument is of type ‘long unsigned int’ after cc5a080c ("efi: Pass boot services variable info to runtime code"). Reported-by: NPaul Bolle <pebolle@tiscali.nl> Cc: Matthew Garrett <matthew.garrett@nebula.com> Signed-off-by: NBorislav Petkov <bp@suse.de> Signed-off-by: NMatt Fleming <matt.fleming@intel.com>
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- 23 4月, 2013 11 次提交
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由 Shawn Guo 提交于
Commit edc7cb2e (usb: phy: make it a menuconfig) makes USB_MXS_PHY be a sub-item of menuconfig symbol USB_PHY. This change gets the selection of CONFIG_USB_MXS_PHY in mxs_defconfig lost. Hence the boot stops at the point below. [ 1.600867] ci_hdrc ci_hdrc.0: doesn't support gadget [ 1.606282] ci_hdrc ci_hdrc.0: EHCI Host Controller [ 1.613522] ci_hdrc ci_hdrc.0: new USB bus registered, assigned bus number 1 Add CONFIG_USB_PHY to have the CONFIG_USB_MXS_PHY selection back to work. Signed-off-by: NShawn Guo <shawn.guo@linaro.org> Signed-off-by: NFelipe Balbi <balbi@ti.com>
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由 Shawn Guo 提交于
Commit edc7cb2e (usb: phy: make it a menuconfig) makes USB_MXS_PHY be a sub-item of menuconfig symbol USB_PHY. This change gets the selection of CONFIG_USB_MXS_PHY in imx_v6_v7_defconfig lost. Hence the boot stops at the point below. ci_hdrc ci_hdrc.0: doesn't support gadget ci_hdrc ci_hdrc.0: EHCI Host Controller ci_hdrc ci_hdrc.0: new USB bus registered, assigned bus number 1 Add CONFIG_USB_PHY to have the CONFIG_USB_MXS_PHY selection back to work. Signed-off-by: NShawn Guo <shawn.guo@linaro.org> Signed-off-by: NFelipe Balbi <balbi@ti.com>
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由 Heiko Carstens 提交于
Kay Sievers reported that coreutils' stat tool has a problem with s390's statfs[64] definition: > The definition of struct statfs::f_type needs a fix. s390 is the only > architecture in the kernel that uses an int and expects magic > constants lager than INT_MAX to fit into. > > A fix is needed to make Fedora boot on s390, it currently fails to do > so. Userspace does not want to add code to paper-over this issue. [...] > Even coreutils cannot handle it: > #define RAMFS_MAGIC 0x858458f6 > # stat -f -c%t / > ffffffff858458f6 > > #define BTRFS_SUPER_MAGIC 0x9123683E > # stat -f -c%t /mnt > ffffffff9123683e The bug is caused by an implicit sign extension within the stat tool: out_uint_x (pformat, prefix_len, statfsbuf->f_type); where the format finally will be "%lx". A similar problem can be found in the 'tail' tool. s390 is the only architecture which has an int type f_type member in struct statfs[64]. Other architectures have either unsigned ints or long values, so that the problem doesn't occur there. Therefore change the type of the f_type member to unsigned int, so that we get zero extension instead of sign extension when assignment to a long value happens. This patch changes the s390 uapi struct stafs[64] definition in the kernel to contain only unsigned values. This was true for 32 bit builds anyway, since we use the generic uapi header file in that case. So lets not include conditionally the generic uapi header file but have the s390 implementation completely independent. Also fix the types of struct compat_stafs to match reality and move the definition of struct compat_statfs64 to asm/compat.h since it is not part of the api. Reported-by: NKay Sievers <kay@vrfy.org> Signed-off-by: NHeiko Carstens <heiko.carstens@de.ibm.com> Signed-off-by: NMartin Schwidefsky <schwidefsky@de.ibm.com>
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由 Gerald Schaefer 提交于
For offset > PAGE_SIZE, s390_dma_map_pages() will issue a warning and return a wrong dma address. This patch removes the warning and fixes the dma return address calculation. Signed-off-by: NGerald Schaefer <gerald.schaefer@de.ibm.com> Signed-off-by: NMartin Schwidefsky <schwidefsky@de.ibm.com>
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由 Heiko Carstens 提交于
Signed-off-by: NHeiko Carstens <heiko.carstens@de.ibm.com> Signed-off-by: NMartin Schwidefsky <schwidefsky@de.ibm.com>
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由 Heiko Carstens 提交于
The compat definitions are not part of the uapi. So move them to s390's private compat header file. Signed-off-by: NHeiko Carstens <heiko.carstens@de.ibm.com> Signed-off-by: NMartin Schwidefsky <schwidefsky@de.ibm.com>
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由 Heiko Carstens 提交于
Fix this one for !COMPAT: compat.h: In function ‘arch_compat_alloc_user_space’: compat.h:292:2: error: implicit declaration of function ‘is_compat_task’ Signed-off-by: NHeiko Carstens <heiko.carstens@de.ibm.com> Signed-off-by: NMartin Schwidefsky <schwidefsky@de.ibm.com>
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由 Heiko Carstens 提交于
The f_spare field within struct compat_statfs is four bytes larger than within the native 31 bit struct statfs. compat_sys_statfs() clears the f_spare field in user space which means that in compat mode four bytes that are behind the user space supplied struct compat_statfs will be corrupted (zeroed). According to Thomas Gleixner's Linux 2.6 history tree this bug is present since v2.5.74 87880da124 "[PATCH] s390: 31 bit compat.". So it get's fixed shortly before its 10th anniversary. Tough luck. Signed-off-by: NHeiko Carstens <heiko.carstens@de.ibm.com> Signed-off-by: NMartin Schwidefsky <schwidefsky@de.ibm.com>
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由 Martin Schwidefsky 提交于
The gmap_map_segment function creates a special invalid segment table entry with the address of the requested target location in the process address space. The first access will create the connection between the gmap segment table and the target page table of the main process. If two threads do this concurrently both will walk the page tables and allocate a gmap_rmap structure for the same segment table entry. To avoid the race recheck the segment table entry after taking to page table lock. Signed-off-by: NMartin Schwidefsky <schwidefsky@de.ibm.com> -
由 Heiko Carstens 提交于
Implement gmap_translate() function which translates a guest absolute address to a user space process address without establishing the guest page table entries. This is useful for kvm guest address translations where no memory access is expected to happen soon (e.g. tprot exception handler). Signed-off-by: NHeiko Carstens <heiko.carstens@de.ibm.com> Reviewed-by: NChristian Borntraeger <borntraeger@de.ibm.com> Signed-off-by: NMartin Schwidefsky <schwidefsky@de.ibm.com>
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由 Ralf Baechle 提交于
This reverts commit c17a6554. Manuel Lauss writes: lmo commit c17a6554 (MIPS: page.h: Provide more readable definition for PAGE_MASK) apparently breaks ioremap of 36-bit addresses on my Alchemy systems (PCI and PCMCIA) The reason is that in arch/mips/mm/ioremap.c line 157 (phys_addr &= PAGE_MASK) bits 32-35 are cut off. Seems the new PAGE_MASK is explicitly 32bit, or one could make it signed instead of unsigned long.
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- 20 4月, 2013 3 次提交
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由 H. Peter Anvin 提交于
For each CPU vendor that implements CPU microcode patching, there will be a minimum family for which this is implemented. Verify this minimum level of support. This can be done in the dispatch function or early in the application functions. Doing the latter turned out to be somewhat awkward because of the ineviable split between the BSP and the AP paths, and rather than pushing deep into the application functions, do this in the dispatch function. Reported-by: N"Bryan O'Donoghue" <bryan.odonoghue.lkml@nexus-software.ie> Suggested-by: NBorislav Petkov <bp@alien8.de> Cc: Fenghua Yu <fenghua.yu@intel.com> Link: http://lkml.kernel.org/r/1366392183-4149-1-git-send-email-bryan.odonoghue.lkml@nexus-software.ie
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由 David S. Miller 提交于
As reported by Dave Kleikamp, when we emit cross calls to do batched TLB flush processing we have a race because we do not synchronize on the sibling cpus completing the cross call. So meanwhile the TLB batch can be reset (tb->tlb_nr set to zero, etc.) and either flushes are missed or flushes will flush the wrong addresses. Fix this by using generic infrastructure to synchonize on the completion of the cross call. This first required getting the flush_tlb_pending() call out from switch_to() which operates with locks held and interrupts disabled. The problem is that smp_call_function_many() cannot be invoked with IRQs disabled and this is explicitly checked for with WARN_ON_ONCE(). We get the batch processing outside of locked IRQ disabled sections by using some ideas from the powerpc port. Namely, we only batch inside of arch_{enter,leave}_lazy_mmu_mode() calls. If we're not in such a region, we flush TLBs synchronously. 1) Get rid of xcall_flush_tlb_pending and per-cpu type implementations. 2) Do TLB batch cross calls instead via: smp_call_function_many() tlb_pending_func() __flush_tlb_pending() 3) Batch only in lazy mmu sequences: a) Add 'active' member to struct tlb_batch b) Define __HAVE_ARCH_ENTER_LAZY_MMU_MODE c) Set 'active' in arch_enter_lazy_mmu_mode() d) Run batch and clear 'active' in arch_leave_lazy_mmu_mode() e) Check 'active' in tlb_batch_add_one() and do a synchronous flush if it's clear. 4) Add infrastructure for synchronous TLB page flushes. a) Implement __flush_tlb_page and per-cpu variants, patch as needed. b) Likewise for xcall_flush_tlb_page. c) Implement smp_flush_tlb_page() to invoke the cross-call. d) Wire up global_flush_tlb_page() to the right routine based upon CONFIG_SMP 5) It turns out that singleton batches are very common, 2 out of every 3 batch flushes have only a single entry in them. The batch flush waiting is very expensive, both because of the poll on sibling cpu completeion, as well as because passing the tlb batch pointer to the sibling cpus invokes a shared memory dereference. Therefore, in flush_tlb_pending(), if there is only one entry in the batch perform a completely asynchronous global_flush_tlb_page() instead. Reported-by: NDave Kleikamp <dave.kleikamp@oracle.com> Signed-off-by: NDavid S. Miller <davem@davemloft.net> Acked-by: NDave Kleikamp <dave.kleikamp@oracle.com> -
由 Stephen Boyd 提交于
cyc_to_sched_clock() is called by sched_clock() and cyc_to_ns() is called by cyc_to_sched_clock(). I suspect that some compilers inline both of these functions into sched_clock() and so we've been getting away without having a notrace marking. It seems that my compiler isn't inlining cyc_to_sched_clock() though, so I'm hitting a recursion bug when I enable the function graph tracer, causing my system to crash. Marking these functions notrace fixes it. Technically cyc_to_ns() doesn't need the notrace because it's already marked inline, but let's just add it so that if we ever remove inline from that function it doesn't blow up. Signed-off-by: NStephen Boyd <sboyd@codeaurora.org> Signed-off-by: NRussell King <rmk+kernel@arm.linux.org.uk>
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- 19 4月, 2013 2 次提交
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由 Waiman Long 提交于
Linus suggested that probably all the supported architectures can allow a negative mutex count without incorrect behavior, so we can then back out the architecture specific change and allow the mutex count to go to any negative number. That should further reduce contention for non-x86 architecture. Suggested-by: NLinus Torvalds <torvalds@linux-foundation.org> Signed-off-by: NWaiman Long <Waiman.Long@hp.com> Cc: Andrew Morton <akpm@linux-foundation.org> Cc: Peter Zijlstra <a.p.zijlstra@chello.nl> Cc: Thomas Gleixner <tglx@linutronix.de> Cc: Chandramouleeswaran Aswin <aswin@hp.com> Cc: Davidlohr Bueso <davidlohr.bueso@hp.com> Cc: Norton Scott J <scott.norton@hp.com> Cc: Rik van Riel <riel@redhat.com> Cc: Paul E. McKenney <paulmck@linux.vnet.ibm.com> Cc: David Howells <dhowells@redhat.com> Cc: Dave Jones <davej@redhat.com> Cc: Clark Williams <williams@redhat.com> Cc: Peter Zijlstra <peterz@infradead.org> Link: http://lkml.kernel.org/r/1366226594-5506-5-git-send-email-Waiman.Long@hp.comSigned-off-by: NIngo Molnar <mingo@kernel.org>
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由 Waiman Long 提交于
In the __mutex_lock_common() function, an initial entry into the lock slow path will cause two atomic_xchg instructions to be issued. Together with the atomic decrement in the fast path, a total of three atomic read-modify-write instructions will be issued in rapid succession. This can cause a lot of cache bouncing when many tasks are trying to acquire the mutex at the same time. This patch will reduce the number of atomic_xchg instructions used by checking the counter value first before issuing the instruction. The atomic_read() function is just a simple memory read. The atomic_xchg() function, on the other hand, can be up to 2 order of magnitude or even more in cost when compared with atomic_read(). By using atomic_read() to check the value first before calling atomic_xchg(), we can avoid a lot of unnecessary cache coherency traffic. The only downside with this change is that a task on the slow path will have a tiny bit less chance of getting the mutex when competing with another task in the fast path. The same is true for the atomic_cmpxchg() function in the mutex-spin-on-owner loop. So an atomic_read() is also performed before calling atomic_cmpxchg(). The mutex locking and unlocking code for the x86 architecture can allow any negative number to be used in the mutex count to indicate that some tasks are waiting for the mutex. I am not so sure if that is the case for the other architectures. So the default is to avoid atomic_xchg() if the count has already been set to -1. For x86, the check is modified to include all negative numbers to cover a larger case. The following table shows the jobs per minutes (JPM) scalability data on an 8-node 80-core Westmere box with a 3.7.10 kernel. The numactl command is used to restrict the running of the high_systime workloads to 1/2/4/8 nodes with hyperthreading on and off. +-----------------+-----------+------------+----------+ | Configuration | Mean JPM | Mean JPM | % Change | | | w/o patch | with patch | | +-----------------+-----------------------------------+ | | User Range 1100 - 2000 | +-----------------+-----------------------------------+ | 8 nodes, HT on | 36980 | 148590 | +301.8% | | 8 nodes, HT off | 42799 | 145011 | +238.8% | | 4 nodes, HT on | 61318 | 118445 | +51.1% | | 4 nodes, HT off | 158481 | 158592 | +0.1% | | 2 nodes, HT on | 180602 | 173967 | -3.7% | | 2 nodes, HT off | 198409 | 198073 | -0.2% | | 1 node , HT on | 149042 | 147671 | -0.9% | | 1 node , HT off | 126036 | 126533 | +0.4% | +-----------------+-----------------------------------+ | | User Range 200 - 1000 | +-----------------+-----------------------------------+ | 8 nodes, HT on | 41525 | 122349 | +194.6% | | 8 nodes, HT off | 49866 | 124032 | +148.7% | | 4 nodes, HT on | 66409 | 106984 | +61.1% | | 4 nodes, HT off | 119880 | 130508 | +8.9% | | 2 nodes, HT on | 138003 | 133948 | -2.9% | | 2 nodes, HT off | 132792 | 131997 | -0.6% | | 1 node , HT on | 116593 | 115859 | -0.6% | | 1 node , HT off | 104499 | 104597 | +0.1% | +-----------------+------------+-----------+----------+ At low user range 10-100, the JPM differences were within +/-1%. So they are not that interesting. AIM7 benchmark run has a pretty large run-to-run variance due to random nature of the subtests executed. So a difference of less than +-5% may not be really significant. This patch improves high_systime workload performance at 4 nodes and up by maintaining transaction rates without significant drop-off at high node count. The patch has practically no impact on 1 and 2 nodes system. The table below shows the percentage time (as reported by perf record -a -s -g) spent on the __mutex_lock_slowpath() function by the high_systime workload at 1500 users for 2/4/8-node configurations with hyperthreading off. +---------------+-----------------+------------------+---------+ | Configuration | %Time w/o patch | %Time with patch | %Change | +---------------+-----------------+------------------+---------+ | 8 nodes | 65.34% | 0.69% | -99% | | 4 nodes | 8.70% | 1.02% | -88% | | 2 nodes | 0.41% | 0.32% | -22% | +---------------+-----------------+------------------+---------+ It is obvious that the dramatic performance improvement at 8 nodes was due to the drastic cut in the time spent within the __mutex_lock_slowpath() function. The table below show the improvements in other AIM7 workloads (at 8 nodes, hyperthreading off). +--------------+---------------+----------------+-----------------+ | Workload | mean % change | mean % change | mean % change | | | 10-100 users | 200-1000 users | 1100-2000 users | +--------------+---------------+----------------+-----------------+ | alltests | +0.6% | +104.2% | +185.9% | | five_sec | +1.9% | +0.9% | +0.9% | | fserver | +1.4% | -7.7% | +5.1% | | new_fserver | -0.5% | +3.2% | +3.1% | | shared | +13.1% | +146.1% | +181.5% | | short | +7.4% | +5.0% | +4.2% | +--------------+---------------+----------------+-----------------+ Signed-off-by: NWaiman Long <Waiman.Long@hp.com> Reviewed-by: NDavidlohr Bueso <davidlohr.bueso@hp.com> Reviewed-by: NRik van Riel <riel@redhat.com> Cc: Linus Torvalds <torvalds@linux-foundation.org> Cc: Andrew Morton <akpm@linux-foundation.org> Cc: Peter Zijlstra <a.p.zijlstra@chello.nl> Cc: Thomas Gleixner <tglx@linutronix.de> Cc: Chandramouleeswaran Aswin <aswin@hp.com> Cc: Norton: Scott J <scott.norton@hp.com> Cc: Paul E. McKenney <paulmck@linux.vnet.ibm.com> Cc: David Howells <dhowells@redhat.com> Cc: Dave Jones <davej@redhat.com> Cc: Clark Williams <williams@redhat.com> Cc: Peter Zijlstra <peterz@infradead.org> Link: http://lkml.kernel.org/r/1366226594-5506-3-git-send-email-Waiman.Long@hp.comSigned-off-by: NIngo Molnar <mingo@kernel.org>
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