Raghavendra K T <raghavendra.kt@xxxxxxx> writes: > On 8/31/2023 12:19 AM, Ankur Arora wrote: >> This series adds a multi-page clearing primitive, clear_pages(), >> which enables more effective use of x86 string instructions by >> advertising the real region-size to be cleared. >> Region-size can be used as a hint by uarchs to optimize the >> clearing. >> Also add allow_resched() which marks a code-section as allowing >> rescheduling in the irqentry_exit path. This allows clear_pages() >> to get by without having to call cond_sched() periodically. >> (preempt_model_full() already handles this via >> irqentry_exit_cond_resched(), so we handle this similarly for >> preempt_model_none() and preempt_model_voluntary().) >> > > Hello Ankur, > Thansk for the patches. > > I tried the patches, Improvements look similar to V1 (even without > circuitous chunk optimizations.) Thanks for testing Raghu. > STill we see similar 50-60% improvement for 1G and 2M page sizes. > > SUT: Bergamo > CPU family: 25 > Model: 160 > Thread(s) per core: 2 > Core(s) per socket: 128 > Socket(s): 2 > > NUMA: > NUMA node(s): 2 > NUMA node0 CPU(s): 0-127,256-383 > NUMA node1 CPU(s): 128-255,384-511 > > Test: Use mmap(MAP_HUGETLB) to demand a fault on 64GB region (NUMA node0), for > both base-hugepage-size=2M and 1GB > Current result is with thp = always, but madv also did not make much difference. > perf stat -r 10 -d -d numactl -m 0 -N 0 <test> > > time in seconds elapsed (average of 10 runs) (lower = better) > > Result: > base: mm/clear_huge_page > patched: x86/clear_huge_page > > page-size base patched Improvement % > 2M 5.0779 2.50623 50.64 > 1G 2.50623 1.012439 59.60 Seems like Bergamo improves over Milan for both 4K BW, and also for extent=2MB/extent=1GB. > Please feel free to carry: > > Tested-by: Raghavendra K T <raghavendra.kt@xxxxxxx> > for any minor changes. Thank you. Will add. -- ankur
