On Fri, 12 Jan 2024 15:35:24 +0800 "Bang Li" <libang.li@xxxxxxxxxxxx> wrote: > Compaction will be triggered when we write 1 to '/proc/sys/vm/ > compact_memory'. During the execution of the process, when we send > SIGKILL to terminate the compaction, the process does not exit > immediately. Instead, it will continue to loop through the remaining > zones and nodes before exiting. > > in my environment: > > [root]# cat /proc/buddyinfo > Node 0, zone DMA 1 1 1 0 2 1 1 0 1 1 3 > Node 0, zone DMA32 1666 1123 804 625 488 356 321 278 209 178 250 > Node 0, zone Normal 58852 83160 49983 9812 2287 1229 19604 24471 10346 5219 12205 > [root]# echo 1 > /sys/kernel/debug/tracing/events/compaction/mm_compaction_end/enable > > before the patch: > > [root]# timeout --signal=SIGKILL 0.002 bash -c 'echo 1 > /proc/sys/vm/compact_memory' > [root]# cat /sys/kernel/debug/tracing/trace_pipe > <...>-26494 [014] ..... 226.468993: mm_compaction_end: zone_start=0x1 migrate_pfn=0xe00 free_pfn=0xe00 zone_end=0x1000, mode=sync status=complete > <...>-26494 [014] ..... 226.469718: mm_compaction_end: zone_start=0x1000 migrate_pfn=0x20a80 free_pfn=0xffe00 zone_end=0x100000, mode=sync status=contended > <...>-26494 [014] ..... 226.469720: mm_compaction_end: zone_start=0x100000 migrate_pfn=0x100000 free_pfn=0x307fe00 zone_end=0x3080000, mode=sync status=contended > > after the patch: > > [root]# timeout --signal=SIGKILL 0.002 bash -c 'echo 1 > /proc/sys/vm/compact_memory' > [root]# cat /sys/kernel/debug/tracing/trace_pipe > <...>-17491 [053] ..... 109.005387: mm_compaction_end: zone_start=0x1 migrate_pfn=0xe00 free_pfn=0xe00 zone_end=0x1000, mode=sync status=complete > <...>-17491 [053] ..... 109.006139: mm_compaction_end: zone_start=0x1000 migrate_pfn=0x22220 free_pfn=0xffe00 zone_end=0x100000, mode=sync status=contended > > Although it exits quickly after receiving the SIGKILL signal, a better > solution is to terminate the loop early after receiving the SIGKILL > signal. > What is the use case here? The requirement? Why is this change valuable to anyone?
