- 20 3月, 2006 38 次提交
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由 David S. Miller 提交于
Signed-off-by: NDavid S. Miller <davem@davemloft.net>
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由 David S. Miller 提交于
This is good for up to %50 performance improvement of some test cases. The problem has been the race conditions, and hopefully I've plugged them all up here. 1) There was a serious race in switch_mm() wrt. lazy TLB switching to and from kernel threads. We could erroneously skip a tsb_context_switch() and thus use a stale TSB across a TSB grow event. There is a big comment now in that function describing exactly how it can happen. 2) All code paths that do something with the TSB need to be guarded with the mm->context.lock spinlock. This makes page table flushing paths properly synchronize with both TSB growing and TLB context changes. 3) TSB growing events are moved to the end of successful fault processing. Previously it was in update_mmu_cache() but that is deadlock prone. At the end of do_sparc64_fault() we hold no spinlocks that could deadlock the TSB grow sequence. We also have dropped the address space semaphore. While we're here, add prefetching to the copy_tsb() routine and put it in assembler into the tsb.S file. This piece of code is quite time critical. There are some small negative side effects to this code which can be improved upon. In particular we grab the mm->context.lock even for the tsb insert done by update_mmu_cache() now and that's a bit excessive. We can get rid of that locking, and the same lock taking in flush_tsb_user(), by disabling PSTATE_IE around the whole operation including the capturing of the tsb pointer and tsb_nentries value. That would work because anyone growing the TSB won't free up the old TSB until all cpus respond to the TSB change cross call. I'm not quite so confident in that optimization to put it in right now, but eventually we might be able to and the description is here for reference. This code seems very solid now. It passes several parallel GCC bootstrap builds, and our favorite "nut cruncher" stress test which is a full "make -j8192" build of a "make allmodconfig" kernel. That puts about 256 processes on each cpu's run queue, makes lots of process cpu migrations occur, causes lots of page table and TLB flushing activity, incurs many context version number changes, and it swaps the machine real far out to disk even though there is 16GB of ram on this test system. :-) Signed-off-by: NDavid S. Miller <davem@davemloft.net>
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由 David S. Miller 提交于
The page->flags manipulations done by the D-cache dirty state tracking was broken because the constants were not marked with "UL" to make them 64-bit, which means we were clobbering the upper 32-bits of page->flags all the time. This doesn't jive well with sparsemem which stores the section and indexing information in the top 32-bits of page->flags. This is yet another sparc64 bug which has been with us forever. While we're here, tidy up some things in bootmem_init() and paginig_init(): 1) Pass min_low_pfn to init_bootmem_node(), it's identical to (phys_base >> PAGE_SHIFT) but we should use consistent with the variable names we print in CONFIG_BOOTMEM_DEBUG 2) max_mapnr, although no longer used, was being set inaccurately, we shouldn't subtract pfn_base any more. 3) All the games with phys_base in the zones_*[] arrays we pass to free_area_init_node() are no longer necessary. Thanks to Josh Grebe and Fabbione for the bug reports and testing. Fix also verified locally on an SB2500 which had a memory layout that triggered the same problem. Signed-off-by: NDavid S. Miller <davem@davemloft.net>
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由 David S. Miller 提交于
This has been pending for a long time, and the fact that we waste a ton of ram on some configurations kind of pushed things over the edge. Signed-off-by: NDavid S. Miller <davem@davemloft.net>
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由 David S. Miller 提交于
1) Always spin_lock_init() in init_context(). The caller essentially clears it out, or copies the mm info from the parent. In both cases we need to explicitly initialize the spinlock. 2) Always do explicit IRQ disabling while taking mm->context.lock and ctx_alloc_lock. Signed-off-by: NDavid S. Miller <davem@davemloft.net>
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由 David S. Miller 提交于
If we were aligned, but didn't have at least 256MB left to process, we would loop forever. Thanks to fabbione for the report and testing the fix. Signed-off-by: NDavid S. Miller <davem@davemloft.net>
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由 David S. Miller 提交于
Don't try to avoid putting non-base page sized entries into the user TSB. It actually costs us more to check this than it helps. Eventually we'll have a multiple TSB scheme for user processes. Once a process starts using larger pages, we'll allocate and use such a TSB. Signed-off-by: NDavid S. Miller <davem@davemloft.net>
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由 David S. Miller 提交于
It is totally wasted work, since we have no D-cache aliasing issues on sun4v. Signed-off-by: NDavid S. Miller <davem@davemloft.net>
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由 David S. Miller 提交于
The context allocation scheme we use depends upon there being a 1<-->1 mapping from cpu to physical TLB for correctness. Chips like Niagara break this assumption. So what we do is notify all cpus with a cross call when the context version number changes, and if necessary this makes them allocate a valid context for the address space they are running at the time. Stress tested with make -j1024, make -j2048, and make -j4096 kernel builds on a 32-strand, 8 core, T2000 with 16GB of ram. Signed-off-by: NDavid S. Miller <davem@davemloft.net>
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由 David S. Miller 提交于
SBUS flash driver needs it. Noticed by Fabbione. Signed-off-by: NDavid S. Miller <davem@davemloft.net>
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由 David S. Miller 提交于
It can map all of the linear kernel mappings with zero TSB hash conflicts for systems with 16GB or less ram. In such cases, on SUN4V, once we load up this TSB the first time with all the mappings, we never take a linear kernel mapping TLB miss ever again, the hypervisor handles them all. Signed-off-by: NDavid S. Miller <davem@davemloft.net>
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由 David S. Miller 提交于
We use a bitmap, one bit for every 256MB of memory. If the bit is set we can use a 256MB PTE for linear mappings, else we have to use a 4MB PTE. SUN4V support is there, and we can very easily add support for Panther cpu 256MB PTEs in the future. Signed-off-by: NDavid S. Miller <davem@davemloft.net>
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由 David S. Miller 提交于
For drivers/media/*, noticed by Fabbione. Signed-off-by: NDavid S. Miller <davem@davemloft.net>
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由 David S. Miller 提交于
The SUN4V convention with non-shared TSBs is that the context bit of the TAG is clear. So we have to choose an "invalid" bit and initialize new TSBs appropriately. Otherwise a zero TAG looks "valid". Make sure, for the window fixup cases, that we use the right global registers and that we don't potentially trample on the live global registers in etrap/rtrap handling (%g2 and %g6) and that we put the missing virtual address properly in %g5. Signed-off-by: NDavid S. Miller <davem@davemloft.net>
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由 David S. Miller 提交于
Signed-off-by: NDavid S. Miller <davem@davemloft.net>
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由 David S. Miller 提交于
It should be 1, not 0. Signed-off-by: NDavid S. Miller <davem@davemloft.net>
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由 David S. Miller 提交于
Signed-off-by: NDavid S. Miller <davem@davemloft.net>
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由 David S. Miller 提交于
This handles the SUN4U vs SUN4V PTE layout differences with near zero performance cost. Signed-off-by: NDavid S. Miller <davem@davemloft.net>
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由 David S. Miller 提交于
Signed-off-by: NDavid S. Miller <davem@davemloft.net>
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由 David S. Miller 提交于
Yes, you heard it right, they changed the PTE layout for SUN4V. Ho hum... This is the simple and inefficient way to support this. It'll get optimized, don't worry. Signed-off-by: NDavid S. Miller <davem@davemloft.net>
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由 David S. Miller 提交于
We do this right after we take over the trap table from OBP. Signed-off-by: NDavid S. Miller <davem@davemloft.net>
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由 David S. Miller 提交于
This is where the virtual address of the fault status area belongs. To set it up we don't make a hypervisor call, instead we call OBP's SUNW,set-trap-table with the real address of the fault status area as the second argument. And right before that call we write the virtual address into ASI_SCRATCHPAD vaddr 0x0. Signed-off-by: NDavid S. Miller <davem@davemloft.net>
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由 David S. Miller 提交于
Function goes in %o5, args go in %o0 --> %o5. Signed-off-by: NDavid S. Miller <davem@davemloft.net>
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由 David S. Miller 提交于
We look for "SUNW,sun4v" in the 'compatible' property of the root OBP device tree node. Protect every %ver register access, to make sure it is not touched on sun4v, as %ver is hyperprivileged there. Lock kernel TLB entries using hypervisor calls instead of calls into OBP. Signed-off-by: NDavid S. Miller <davem@davemloft.net>
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由 David S. Miller 提交于
sun4v uses ASI_MMU instead of ASI_DMMU Signed-off-by: NDavid S. Miller <davem@davemloft.net>
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由 David S. Miller 提交于
Signed-off-by: NDavid S. Miller <davem@davemloft.net>
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由 David S. Miller 提交于
Things are a little tricky because, unlike sun4u, we have to: 1) do a hypervisor trap to do the TLB load. 2) do the TSB lookup calculations by hand Signed-off-by: NDavid S. Miller <davem@davemloft.net>
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由 David S. Miller 提交于
And more consistently check cheetah{,_plus} instead of assuming anything not spitfire is cheetah{,_plus}. Signed-off-by: NDavid S. Miller <davem@davemloft.net>
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由 David S. Miller 提交于
There are several tricky races involved with growing the TSB. So just use base-size TSBs for user contexts and we can revisit enabling this later. One part of the SMP problems is that tsb_context_switch() can see partially updated TSB configuration state if tsb_grow() is running in parallel. That's easily solved with a seqlock taken as a writer by tsb_grow() and taken as a reader to capture all the TSB config state in tsb_context_switch(). Then there is flush_tsb_user() running in parallel with a tsb_grow(). In theory we could take the seqlock as a reader there too, and just resample the TSB pointer and reflush but that looks really ugly. Lastly, I believe there is a case with threads that results in a TSB entry lock bit being set spuriously which will cause the next access to that TSB entry to wedge the cpu (since the TSB entry lock bit will never clear). It's either copy_tsb() or some bug elsewhere in the TSB assembly. Signed-off-by: NDavid S. Miller <davem@davemloft.net>
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由 David S. Miller 提交于
This way we don't need to lock the TSB into the TLB. The trick is that every TSB load/store is registered into a special instruction patch section. The default uses virtual addresses, and the patch instructions use physical address load/stores. We can't do this on all chips because only cheetah+ and later have the physical variant of the atomic quad load. Signed-off-by: NDavid S. Miller <davem@davemloft.net>
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由 David S. Miller 提交于
Signed-off-by: NDavid S. Miller <davem@davemloft.net>
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由 David S. Miller 提交于
No longer used, and move extern declaration to a header file. Signed-off-by: NDavid S. Miller <davem@davemloft.net>
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由 David S. Miller 提交于
It is totally unnecessary complexity. After we take over the trap table, we handle all PROM tlb misses fully. Signed-off-by: NDavid S. Miller <davem@davemloft.net>
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由 David S. Miller 提交于
Signed-off-by: NDavid S. Miller <davem@davemloft.net>
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由 David S. Miller 提交于
As the RSS grows, grow the TSB in order to reduce the likelyhood of hash collisions and thus poor hit rates in the TSB. This definitely needs some serious tuning. Signed-off-by: NDavid S. Miller <davem@davemloft.net>
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由 David S. Miller 提交于
Taking a nod from the powerpc port. With the per-cpu caching of both the page allocator and SLAB, the pgtable quicklist scheme becomes relatively silly and primitive. Signed-off-by: NDavid S. Miller <davem@davemloft.net>
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由 David S. Miller 提交于
Unlike the virtual page tables, the new TSB scheme does not require this ugly hack. Signed-off-by: NDavid S. Miller <davem@davemloft.net>
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由 David S. Miller 提交于
We now use the TSB hardware assist features of the UltraSPARC MMUs. SMP is currently knowingly broken, we need to find another place to store the per-cpu base pointers. We hid them away in the TSB base register, and that obviously will not work any more :-) Another known broken case is non-8KB base page size. Also noticed that flush_tlb_all() is not referenced anywhere, only the internal __flush_tlb_all() (local cpu only) is used by the sparc64 port, so we can get rid of flush_tlb_all(). The kernel gets it's own 8KB TSB (swapper_tsb) and each address space gets it's own private 8K TSB. Later we can add code to dynamically increase the size of per-process TSB as the RSS grows. An 8KB TSB is good enough for up to about a 4MB RSS, after which the TSB starts to incur many capacity and conflict misses. We even accumulate OBP translations into the kernel TSB. Another area for refinement is large page size support. We could use a secondary address space TSB to handle those. Signed-off-by: NDavid S. Miller <davem@davemloft.net>
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- 13 10月, 2005 1 次提交
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由 David S. Miller 提交于
The sequence to move over to the Linux trap tables from the firmware ones needs to be more air tight. It turns out that to be %100 safe we do need to be able to translate OBP mappings in our TLB miss handlers early. In order not to eat up a lot of kernel image memory with static page tables, just use the translations array in the OBP TLB miss handlers. That solves the bulk of the problem. Furthermore, to make sure the OBP TLB miss path will work even before the fixed MMU globals are loaded, explicitly load %g1 to TLB_SFSR at the beginning of the i-TLB and d-TLB miss handlers. To ease the OBP TLB miss walking of the prom_trans[] array, we sort it then delete all of the non-OBP entries in there (for example, there are entries for the kernel image itself which we're not interested in at all). We also save about 32K of kernel image size with this change. Not a bad side effect :-) There are still some reasons why trampoline.S can't use the setup_trap_table() yet. The most noteworthy are: 1) OBP boots secondary processors with non-bias'd stack for some reason. This is easily fixed by using a small bootup stack in the kernel image explicitly for this purpose. 2) Doing a firmware call via the normal C call prom_set_trap_table() goes through the whole OBP enter/exit sequence that saves and restores OBP and Linux kernel state in the MMUs. This path unfortunately does a "flush %g6" while loading up the OBP locked TLB entries for the firmware call. If we setup the %g6 in the trampoline.S code properly, that is in the PAGE_OFFSET linear mapping, but we're not on the kernel trap table yet so those addresses won't translate properly. One idea is to do a by-hand firmware call like we do in the early bootup code and elsewhere here in trampoline.S But this fails as well, as aparently the secondary processors are not booted with OBP's special locked TLB entries loaded. These are necessary for the firwmare to processes TLB misses correctly up until the point where we take over the trap table. This does need to be resolved at some point. Signed-off-by: NDavid S. Miller <davem@davemloft.net>
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- 06 10月, 2005 1 次提交
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由 David S. Miller 提交于
By allocating early memory for the firmware page tables, we can write over the beginning of the initrd image. So what we do now is: 1) Read in firmware translations table while still on the firmware's trap table. 2) Switch to Linux trap table. 3) Init bootmem. 4) Build firmware page tables using __alloc_bootmem(). And this keeps the initrd from being clobbered. Signed-off-by: NDavid S. Miller <davem@davemloft.net>
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