On 2019/07/08 12:35, Max Kellermann <[email protected]> wrote: > one of our web servers got repeatedly stuck in the memory compaction > code; two PHP processes have been busy at 100% inside memory > compaction after a page fault:
This trace maybe helpful as well; the first PHP process: 275.846 compaction:mm_compaction_isolate_migratepages:range=(0x8a48e0 ~ 0x8a48e0) nr_scanned=0 nr_taken=0 LOST 8 events! 275.894 compaction:mm_compaction_isolate_migratepages:range=(0x8a48e0 ~ 0x8a48e0) nr_scanned=0 nr_taken=0 LOST 8 events! 275.942 compaction:mm_compaction_isolate_migratepages:range=(0x8a48e0 ~ 0x8a48e0) nr_scanned=0 nr_taken=0 LOST 8 events! 275.989 compaction:mm_compaction_isolate_migratepages:range=(0x8a48e0 ~ 0x8a48e0) nr_scanned=0 nr_taken=0 This is the other PHP process: 188.501 compaction:mm_compaction_isolate_migratepages:range=(0x169f40 ~ 0x169f40) nr_scanned=0 nr_taken=0 LOST 16 events! 188.600 compaction:mm_compaction_isolate_migratepages:range=(0x169f40 ~ 0x169f40) nr_scanned=0 nr_taken=0 LOST 5 events! 188.643 compaction:mm_compaction_isolate_migratepages:range=(0x169f40 ~ 0x169f40) nr_scanned=0 nr_taken=0 LOST 17 events! 188.742 compaction:mm_compaction_isolate_migratepages:range=(0x169f40 ~ 0x169f40) nr_scanned=0 nr_taken=0 No pages are being scanned at all, start and end are the same. However, since my perf report contains calls to compact_unlock_should_abort(), this means that the loop in isolate_migratepages_block() is not getting skipped completely, therefore the loop is just exiting too early.
