- 30 12月, 2013 1 次提交
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由 Paul E. McKenney 提交于
The powerpc 64-bit __copy_tofrom_user() function uses shifts to handle unaligned invocations. However, these shifts were designed for big-endian systems: On little-endian systems, they must shift in the opposite direction. This commit relies on the C preprocessor to insert the correct shifts into the assembly code. [ This is a rare but nasty LE issue. Most of the time we use the POWER7 optimised __copy_tofrom_user_power7 loop, but when it hits an exception we fall back to the base __copy_tofrom_user loop. - Anton ] Signed-off-by: NPaul E. McKenney <paulmck@linux.vnet.ibm.com> Signed-off-by: NAnton Blanchard <anton@samba.org> Signed-off-by: NBenjamin Herrenschmidt <benh@kernel.crashing.org>
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- 10 7月, 2012 2 次提交
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由 Michael Neuling 提交于
mtocrf define is just a wrapper around the real instructions so we can just use real register names here (ie. lower case). Also remove braces in macro so this is possible. Signed-off-by: NMichael Neuling <mikey@neuling.org> Signed-off-by: NBenjamin Herrenschmidt <benh@kernel.crashing.org>
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由 Michael Neuling 提交于
Anything that uses a constructed instruction (ie. from ppc-opcode.h), need to use the new R0 macro, as %r0 is not going to work. Also convert usages of macros where we are just determining an offset (usually for a load/store), like: std r14,STK_REG(r14)(r1) Can't use STK_REG(r14) as %r14 doesn't work in the STK_REG macro since it's just calculating an offset. Signed-off-by: NMichael Neuling <mikey@neuling.org> Signed-off-by: NBenjamin Herrenschmidt <benh@kernel.crashing.org>
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- 30 4月, 2012 1 次提交
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由 Anton Blanchard 提交于
Remove CONFIG_POWER4_ONLY, the option is badly named and only does two things: - It wraps the MMU segment table code. With feature fixups there is little downside to compiling this in. - It uses the newer mtocrf instruction in various assembly functions. Instead of making this a compile option just do it at runtime via a feature fixup. Signed-off-by: NAnton Blanchard <anton@samba.org> Signed-off-by: NBenjamin Herrenschmidt <benh@kernel.crashing.org>
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- 19 12月, 2011 1 次提交
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由 Anton Blanchard 提交于
Implement a POWER7 optimised copy_to_user/copy_from_user using VMX. For large aligned copies this new loop is over 10% faster, and for large unaligned copies it is over 200% faster. If we take a fault we fall back to the old version, this keeps things relatively simple and easy to verify. On POWER7 unaligned stores rarely slow down - they only flush when a store crosses a 4KB page boundary. Furthermore this flush is handled completely in hardware and should be 20-30 cycles. Unaligned loads on the other hand flush much more often - whenever crossing a 128 byte cache line, or a 32 byte sector if either sector is an L1 miss. Considering this information we really want to get the loads aligned and not worry about the alignment of the stores. Microbenchmarks confirm that this approach is much faster than the current unaligned copy loop that uses shifts and rotates to ensure both loads and stores are aligned. We also want to try and do the stores in cacheline aligned, cacheline sized chunks. If the store queue is unable to merge an entire cacheline of stores then the L2 cache will have to do a read/modify/write. Even worse, we will serialise this with the stores in the next iteration of the copy loop since both iterations hit the same cacheline. Based on this, the new loop does the following things: 1 - 127 bytes Get the source 8 byte aligned and use 8 byte loads and stores. Pretty boring and similar to how the current loop works. 128 - 4095 bytes Get the source 8 byte aligned and use 8 byte loads and stores, 1 cacheline at a time. We aren't doing the stores in cacheline aligned chunks so we will potentially serialise once per cacheline. Even so it is much better than the loop we have today. 4096 - bytes If both source and destination have the same alignment get them both 16 byte aligned, then get the destination cacheline aligned. Do cacheline sized loads and stores using VMX. If source and destination do not have the same alignment, we get the destination cacheline aligned, and use permute to do aligned loads. In both cases the VMX loop should be optimal - we always do aligned loads and stores and are always doing stores in cacheline aligned, cacheline sized chunks. To be able to use VMX we must be careful about interrupts and sleeping. We don't use the VMX loop when in an interrupt (which should be rare anyway) and we wrap the VMX loop in disable/enable_pagefault and fall back to the existing copy_tofrom_user loop if we do need to sleep. The VMX breakpoint of 4096 bytes was chosen using this microbenchmark: http://ozlabs.org/~anton/junkcode/copy_to_user.c Since we are using VMX and there is a cost to saving and restoring the user VMX state there are two broad cases we need to benchmark: - Best case - userspace never uses VMX - Worst case - userspace always uses VMX In reality a userspace process will sit somewhere between these two extremes. Since we need to test both aligned and unaligned copies we end up with 4 combinations. The point at which the VMX loop begins to win is: 0% VMX aligned 2048 bytes unaligned 2048 bytes 100% VMX aligned 16384 bytes unaligned 8192 bytes Considering this is a microbenchmark, the data is hot in cache and the VMX loop has better store queue merging properties we set the breakpoint to 4096 bytes, a little below the unaligned breakpoints. Some future optimisations we can look at: - Looking at the perf data, a significant part of the cost when a task is always using VMX is the extra exception we take to restore the VMX state. As such we should do something similar to the x86 optimisation that restores FPU state for heavy users. ie: /* * If the task has used fpu the last 5 timeslices, just do a full * restore of the math state immediately to avoid the trap; the * chances of needing FPU soon are obviously high now */ preload_fpu = tsk_used_math(next_p) && next_p->fpu_counter > 5; and /* * fpu_counter contains the number of consecutive context switches * that the FPU is used. If this is over a threshold, the lazy fpu * saving becomes unlazy to save the trap. This is an unsigned char * so that after 256 times the counter wraps and the behavior turns * lazy again; this to deal with bursty apps that only use FPU for * a short time */ - We could create a paca bit to mirror the VMX enabled MSR bit and check that first, avoiding multiple calls to calling enable_kernel_altivec. That should help with iovec based system calls like readv. - We could have two VMX breakpoints, one for when we know the user VMX state is loaded into the registers and one when it isn't. This could be a second bit in the paca so we can calculate the break points quickly. - One suggestion from Ben was to save and restore the VSX registers we use inline instead of using enable_kernel_altivec. [BenH: Fixed a problem with preempt and fixed build without CONFIG_ALTIVEC] Signed-off-by: NAnton Blanchard <anton@samba.org> Signed-off-by: NBenjamin Herrenschmidt <benh@kernel.crashing.org>
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- 17 2月, 2010 1 次提交
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由 Anton Blanchard 提交于
Here is a patch from Paul Mackerras that improves the ppc64 copy_tofrom_user. The loop now does 32 bytes at a time and as well as pairing loads and stores. A quick test case that reads 8kB over and over shows the improvement: POWER6: 53% faster POWER7: 51% faster #define _XOPEN_SOURCE 500 #include <stdlib.h> #include <stdio.h> #include <unistd.h> #include <fcntl.h> #include <sys/types.h> #include <sys/stat.h> #define BUFSIZE (8 * 1024) #define ITERATIONS 10000000 int main() { char tmpfile[] = "/tmp/copy_to_user_testXXXXXX"; int fd; char *buf[BUFSIZE]; unsigned long i; fd = mkstemp(tmpfile); if (fd < 0) { perror("open"); exit(1); } if (write(fd, buf, BUFSIZE) != BUFSIZE) { perror("open"); exit(1); } for (i = 0; i < 10000000; i++) { if (pread(fd, buf, BUFSIZE, 0) != BUFSIZE) { perror("pread"); exit(1); } } unlink(tmpfile); return 0; } Signed-off-by: NAnton Blanchard <anton@samba.org> Signed-off-by: NBenjamin Herrenschmidt <benh@kernel.crashing.org>
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- 26 2月, 2009 1 次提交
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由 Mark Nelson 提交于
This fixes a regression introduced by commit a4e22f02 ("powerpc: Update 64bit __copy_tofrom_user() using CPU_FTR_UNALIGNED_LD_STD"). The same bug that existed in the 64bit memcpy() also exists here so fix it here too. The fix is the same as that applied to memcpy() with the addition of fixes for the exception handling code required for __copy_tofrom_user(). This stops us reading beyond the end of the source region we were told to copy. Signed-off-by: NMark Nelson <markn@au1.ibm.com> Signed-off-by: NBenjamin Herrenschmidt <benh@kernel.crashing.org>
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- 19 11月, 2008 1 次提交
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由 Mark Nelson 提交于
In exactly the same way that we updated memcpy() with new feature sections in commit 25d6e2d7 ("powerpc: Update 64bit memcpy() using CPU_FTR_UNALIGNED_LD_STD"), we do the same thing here for __copy_tofrom_user(). Once again this is purely a performance tweak for Cell and Power6 - this has no effect on all the other 64bit powerpc chips. We can make these same changes to __copy_tofrom_user() because the basic copy algorithm is the same as in memcpy() - this version just has all the exception handling logic needed when copying to or from userspace as well as a special case for copying whole 4K pages that are page aligned. CPU_FTR_UNALIGNED_LD_STD CPU was added in commit 4ec577a2 ("powerpc: Add new CPU feature: CPU_FTR_UNALIGNED_LD_STD"). We also make the same simple one line change from cmpldi r1,... to cmpldi cr1,... for consistency. Signed-off-by: NMark Nelson <markn@au1.ibm.com> Signed-off-by: NPaul Mackerras <paulus@samba.org>
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- 13 4月, 2007 1 次提交
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由 Olof Johansson 提交于
mtocrf is a faster single-field mtcrf (move to condition register fields) instruction available in POWER4 and later processors. It can make quite a difference in performance on some implementations, so use it for CONFIG_POWER4_ONLY builds. Signed-off-by: NOlof Johansson <olof@lixom.net> Signed-off-by: NPaul Mackerras <paulus@samba.org>
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- 10 2月, 2006 1 次提交
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由 Jon Mason 提交于
This patch removes all self references and fixes references to files in the now defunct arch/ppc64 tree. I think this accomplises everything wanted, though there might be a few references I missed. Signed-off-by: NJon Mason <jdmason@us.ibm.com> Signed-off-by: NPaul Mackerras <paulus@samba.org>
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- 07 11月, 2005 1 次提交
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由 Benjamin Herrenschmidt 提交于
Adds a new CONFIG_PPC_64K_PAGES which, when enabled, changes the kernel base page size to 64K. The resulting kernel still boots on any hardware. On current machines with 4K pages support only, the kernel will maintain 16 "subpages" for each 64K page transparently. Note that while real 64K capable HW has been tested, the current patch will not enable it yet as such hardware is not released yet, and I'm still verifying with the firmware architects the proper to get the information from the newer hypervisors. Signed-off-by: NBenjamin Herrenschmidt <benh@kernel.crashing.org> Signed-off-by: NLinus Torvalds <torvalds@osdl.org>
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- 10 10月, 2005 1 次提交
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由 Paul Mackerras 提交于
This doesn't change any code, just renames things so we consistently have foo_32.c and foo_64.c where we have separate 32- and 64-bit versions. Signed-off-by: NPaul Mackerras <paulus@samba.org>
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- 26 9月, 2005 1 次提交
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由 Paul Mackerras 提交于
This creates the directory structure under arch/powerpc and a bunch of Kconfig files. It does a first-cut merge of arch/powerpc/mm, arch/powerpc/lib and arch/powerpc/platforms/powermac. This is enough to build a 32-bit powermac kernel with ARCH=powerpc. For now we are getting some unmerged files from arch/ppc/kernel and arch/ppc/syslib, or arch/ppc64/kernel. This makes some minor changes to files in those directories and files outside arch/powerpc. The boot directory is still not merged. That's going to be interesting. Signed-off-by: NPaul Mackerras <paulus@samba.org>
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- 17 4月, 2005 1 次提交
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由 Linus Torvalds 提交于
Initial git repository build. I'm not bothering with the full history, even though we have it. We can create a separate "historical" git archive of that later if we want to, and in the meantime it's about 3.2GB when imported into git - space that would just make the early git days unnecessarily complicated, when we don't have a lot of good infrastructure for it. Let it rip!
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