Vineet Gupta 8d56bec2f2 ARC: [mm] optimize needless full mm TLB flush on munmap ... munmap ends up calling tlb_flush() which for ARC was flushing the entire TLB unconditionally (by moving the MMU to a new ASID) do_munmap unmap_region unmap_vmas unmap_single_vma unmap_page_range tlb_start_vma zap_pud_range tlb_end_vma() tlb_finish_mmu tlb_flush() ---> unconditional flush_tlb_mm() So even a single page munmap, a frequent operation when uClibc dynamic linker (ldso) is loading the dependent shared libraries, would move the the ASID multiple times - needlessly invalidating the pre-faulted TLB entries (and increasing the rate of ASID wraparound + full TLB flush). This is now optimised to only be called if tlb->full_mm (which means for exit/execve) cases only. And for those cases, flush_tlb_mm() is already optimised to be a no-op for mm->mm_users == 0. So essentially there are no mmore full mm flushes - except for fork which anyhow needs it for properly COW'ing parent address space. munmap now needs to do TLB range flush, which is implemented with tlb_end_vma() Results ------- 1. ASID now consistenly moves by 4 during a simple ls (as opposed to 5 or 7 before). 2. LMBench microbenchmark also shows improvements Basic system parameters ------------------------------------------------------------------------------ Host OS Description Mhz tlb cache mem scal pages line par load bytes --------- ------------- ----------------------- ---- ----- ----- ------ ---- 3.9-rc5-0 Linux 3.9.0-r 3.9-rc5-0404-gcc-4.4-ba 80 8 64 1.1000 1 3.9-rc5-0 Linux 3.9.0-r 3.9-rc5-0405-avoid-full 80 8 64 1.1200 1 Processor, Processes - times in microseconds - smaller is better ------------------------------------------------------------------------------ Host OS Mhz null null open slct sig sig fork exec sh call I/O stat clos TCP inst hndl proc proc proc --------- ------------- ---- ---- ---- ---- ---- ---- ---- ---- ---- ---- ---- 3.9-rc5-0 Linux 3.9.0-r 80 4.81 8.69 68.6 118. 239. 8.53 31.6 4839 13.K 34.K 3.9-rc5-0 Linux 3.9.0-r 80 4.46 8.36 53.8 91.3 223. 8.12 24.2 4725 13.K 33.K File & VM system latencies in microseconds - smaller is better ------------------------------------------------------------------------------- Host OS 0K File 10K File Mmap Prot Page 100fd Create Delete Create Delete Latency Fault Fault selct --------- ------------- ------ ------ ------ ------ ------- ----- ------- ----- 3.9-rc5-0 Linux 3.9.0-r 314.7 223.2 1054.9 390.2 3615.0 1.590 20.1 126.6 3.9-rc5-0 Linux 3.9.0-r 265.8 183.8 1014.2 314.1 3193.0 6.910 18.8 110.4 Signed-off-by: Vineet Gupta <vgupta@synopsys.com>		2013-05-07 13:44:00 +05:30
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asm	ARC: [mm] optimize needless full mm TLB flush on munmap	2013-05-07 13:44:00 +05:30
uapi/asm	ARC: make allyesconfig build breakages	2013-03-11 19:01:09 +05:30