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e9f4e0a9fe
I think the flush_tlb_mm_range() code that tries to tune the flush sizes based on the CPU needs to get ripped out for several reasons: 1. It is obviously buggy. It uses mm->total_vm to judge the task's footprint in the TLB. It should certainly be using some measure of RSS, *NOT* ->total_vm since only resident memory can populate the TLB. 2. Haswell, and several other CPUs are missing from the intel_tlb_flushall_shift_set() function. Thus, it has been demonstrated to bitrot quickly in practice. 3. It is plain wrong in my vm: [ 0.037444] Last level iTLB entries: 4KB 0, 2MB 0, 4MB 0 [ 0.037444] Last level dTLB entries: 4KB 0, 2MB 0, 4MB 0 [ 0.037444] tlb_flushall_shift: 6 Which leads to it to never use invlpg. 4. The assumptions about TLB refill costs are wrong: http://lkml.kernel.org/r/1337782555-8088-3-git-send-email-alex.shi@intel.com (more on this in later patches) 5. I can not reproduce the original data: https://lkml.org/lkml/2012/5/17/59 I believe the sample times were too short. Running the benchmark in a loop yields times that vary quite a bit. Note that this leaves us with a static ceiling of 1 page. This is a conservative, dumb setting, and will be revised in a later patch. This also removes the code which attempts to predict whether we are flushing data or instructions. We expect instruction flushes to be relatively rare and not worth tuning for explicitly. Signed-off-by: Dave Hansen <dave.hansen@linux.intel.com> Link: http://lkml.kernel.org/r/20140731154055.ABC88E89@viggo.jf.intel.com Acked-by: Rik van Riel <riel@redhat.com> Acked-by: Mel Gorman <mgorman@suse.de> Signed-off-by: H. Peter Anvin <hpa@linux.intel.com> |
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