On 2024/2/3 00:26, Johannes Weiner wrote: > On Fri, Feb 02, 2024 at 08:57:38PM +0800, Chengming Zhou wrote: >> On 2024/2/2 02:12, Johannes Weiner wrote: >>> Caching "swapout work" is helpful when the system is thrashing. Then >>> recently swapped in pages might get swapped out again very soon. It >>> certainly makes sense with conventional swap, because keeping a clean >>> copy on the disk saves IO work and doesn't cost any additional memory. >>> >>> But with zswap, it's different. It saves some compression work on a >>> thrashing page. But the act of keeping compressed memory contributes >>> to a higher rate of thrashing. And that can cause IO in other places >>> like zswap writeback and file memory. >> >> [...] A/B test kernel building in tmpfs directory, memory.max=2GB. >> (zswap writeback enabled and shrinker_enabled, one 50GB swapfile) >> >> From the below results, exclusive mode has fewer scan and refault. >> >> zswap-invalidate-entry zswap-invalidate-entry-exclusive >> real 63.80 63.01 >> user 1063.83 1061.32 >> sys 290.31 266.15 >> zswap-invalidate-entry zswap-invalidate-entry-exclusive >> workingset_refault_anon 2383084.40 1976397.40 >> workingset_refault_file 44134.00 45689.40 >> workingset_activate_anon 837878.00 728441.20 >> workingset_activate_file 4710.00 4085.20 >> workingset_restore_anon 732622.60 639428.40 >> workingset_restore_file 1007.00 926.80 >> workingset_nodereclaim 0.00 0.00 >> pgscan 14343003.40 12409570.20 >> pgscan_kswapd 0.00 0.00 >> pgscan_direct 14343003.40 12409570.20 >> pgscan_khugepaged 0.00 0.00 > > That's perfect. Thanks! > > Would you mind adding all of the above into the changelog? Yeah, will do. Thanks! > > With that, > > Acked-by: Johannes Weiner <hannes@xxxxxxxxxxx>
