From: Kienan Stewart Date: Mon, 25 Mar 2024 14:30:32 +0000 (-0400) Subject: Fix: mm_compaction_migratepages changed in linux 6.9-rc1 X-Git-Url: http://git.liburcu.org/?p=lttng-modules.git;a=commitdiff_plain;h=f4a6415f8d5fa447868d1fdc7119e0a328966379 Fix: mm_compaction_migratepages changed in linux 6.9-rc1 See upstream commit: commit ab755bf4249b992fc2140d615ab0a686d50765b4 Author: Baolin Wang Date: Tue Feb 20 14:16:31 2024 +0800 mm: compaction: update the cc->nr_migratepages when allocating or freeing the freepages Currently we will use 'cc->nr_freepages >= cc->nr_migratepages' comparison to ensure that enough freepages are isolated in isolate_freepages(), however it just decreases the cc->nr_freepages without updating cc->nr_migratepages in compaction_alloc(), which will waste more CPU cycles and cause too many freepages to be isolated. So we should also update the cc->nr_migratepages when allocating or freeing the freepages to avoid isolating excess freepages. And I can see fewer free pages are scanned and isolated when running thpcompact on my Arm64 server: k6.7 k6.7_patched Ops Compaction pages isolated 120692036.00 118160797.00 Ops Compaction migrate scanned 131210329.00 154093268.00 Ops Compaction free scanned 1090587971.00 1080632536.00 Ops Compact scan efficiency 12.03 14.26 Moreover, I did not see an obvious latency improvements, this is likely because isolating freepages is not the bottleneck in the thpcompact test case. k6.7 k6.7_patched Amean fault-both-1 1089.76 ( 0.00%) 1080.16 * 0.88%* Amean fault-both-3 1616.48 ( 0.00%) 1636.65 * -1.25%* Amean fault-both-5 2266.66 ( 0.00%) 2219.20 * 2.09%* Amean fault-both-7 2909.84 ( 0.00%) 2801.90 * 3.71%* Amean fault-both-12 4861.26 ( 0.00%) 4733.25 * 2.63%* Amean fault-both-18 7351.11 ( 0.00%) 6950.51 * 5.45%* Amean fault-both-24 9059.30 ( 0.00%) 9159.99 * -1.11%* Amean fault-both-30 10685.68 ( 0.00%) 11399.02 * -6.68%* Change-Id: I103a43fd1b549360b3fc978fd409b7c17ef3e192 Signed-off-by: Kienan Stewart Signed-off-by: Mathieu Desnoyers --- diff --git a/include/instrumentation/events/compaction.h b/include/instrumentation/events/compaction.h index 7d0c2623..353fe3b5 100644 --- a/include/instrumentation/events/compaction.h +++ b/include/instrumentation/events/compaction.h @@ -54,7 +54,22 @@ LTTNG_TRACEPOINT_EVENT_INSTANCE_MAP(compaction_isolate_template, TP_ARGS(start_pfn, end_pfn, nr_scanned, nr_taken) ) -#if (LTTNG_LINUX_VERSION_CODE >= LTTNG_KERNEL_VERSION(5,18,0) || \ +#if (LTTNG_LINUX_VERSION_CODE >= LTTNG_KERNEL_VERSION(6,9,0)) +LTTNG_TRACEPOINT_EVENT_MAP(mm_compaction_migratepages, + + compaction_migratepages, + + TP_PROTO(unsigned int nr_migratepages, + unsigned int nr_succeeded), + + TP_ARGS(nr_migratepages, nr_succeeded), + + TP_FIELDS( + ctf_integer(unsigned long, nr_migrated, nr_succeeded) + ctf_integer(unsigned long, nr_failed, nr_migratepages - nr_succeeded) + ) +) +#elif (LTTNG_LINUX_VERSION_CODE >= LTTNG_KERNEL_VERSION(5,18,0) || \ LTTNG_RHEL_KERNEL_RANGE(5,14,0,163,0,0, 5,15,0,0,0,0)) LTTNG_TRACEPOINT_EVENT_MAP(mm_compaction_migratepages,