Hi, the current status is, that everything works well / fine since i switched from CONFIG_TRANSPARENT_HUGEPAGE_ALWAYS to CONFIG_TRANSPARENT_HUGEPAGE_MADVISE Am 27.09.19 um 14:45 schrieb Vlastimil Babka: > On 9/19/19 12:21 PM, Stefan Priebe - Profihost AG wrote: >> Kernel 5.2.14 is now running since exactly 7 days and now we can easaly >> view a trend i', not sure if i should post graphs. >> >> Cache size is continuously shrinking while memfree is rising. >> >> While there were 4,5GB free in avg in the beginnen we now have an avg of >> 8GB free memory. >> >> Cache has shrinked from avg 24G to avg 18G. >> >> Memory pressure has rised from avg 0% to avg 0.1% - not much but if you >> look at the graphs it's continuously rising while cache is shrinking and >> memfree is rising. > > Hi, could you try the patch below? I suspect you're hitting a corner > case where compaction_suitable() returns COMPACT_SKIPPED for the > ZONE_DMA, triggering reclaim even if other zones have plenty of free > memory. And should_continue_reclaim() then returns true until twice the > requested page size is reclaimed (compact_gap()). That means 4MB > reclaimed for each THP allocation attempt, which roughly matches the > trace data you preovided previously. > > The amplification to 4MB should be removed in patches merged for 5.4, so > it would be only 32 pages reclaimed per THP allocation. The patch below > tries to remove this corner case completely, and it should be more > visible on your 5.2.x, so please apply it there. so i switched back to 4.19 LTS Kernel - as this is the kernel we run on all our infrastructures. THP is now only in use von kvm host machines. Your patch applies to 4.19 as well - but not sure if it is a good idea to apply it to those machines. Greets, Stefan
