Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx> writes: > On Mon, 8 Apr 2024 20:14:39 +0800 Zhaoyu Liu <liuzhaoyu.zackary@xxxxxxxxxxxxx> wrote: > >> Based on qemu arm64 - latest kernel + 100M memory + 1024M swapfile. >> Create 1G anon mmap and set it to shared, and has two processes >> randomly access the shared memory. When they are racing on swap cache, >> on average, each "alloc_pages_mpol + swapcache_prepare + folio_put" >> took about 1475 us. > > And what effect does this patch have upon the measured time? ANd upon > overall runtime? And the patch will cause increased lock contention, please test with more processes and perhaps HDD swap device too. >> So skip page allocation if SWAP_HAS_CACHE was set, just >> schedule_timeout_uninterruptible and continue to acquire page >> via filemap_get_folio() from swap cache, to speedup >> __read_swap_cache_async. -- Best Regards, Huang, Ying
