The patch titled
Subject: mm/vmscan: throttle reclaim when no progress is being made
has been added to the -mm tree. Its filename is
mm-vmscan-throttle-reclaim-when-no-progress-is-being-made.patch
This patch should soon appear at
https://ozlabs.org/~akpm/mmots/broken-out/mm-vmscan-throttle-reclaim-when-no-progress-is-being-made.patch
and later at
https://ozlabs.org/~akpm/mmotm/broken-out/mm-vmscan-throttle-reclaim-when-no-progress-is-being-made.patch
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*** Remember to use Documentation/process/submit-checklist.rst when testing your code ***
The -mm tree is included into linux-next and is updated
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------------------------------------------------------
From: Mel Gorman <mgorman@xxxxxxxxxxxxxxxxxxx>
Subject: mm/vmscan: throttle reclaim when no progress is being made
Memcg reclaim throttles on congestion if no reclaim progress is made.
This makes little sense, it might be due to writeback or a host of other
factors.
For !memcg reclaim, it's messy. Direct reclaim primarily is throttled in
the page allocator if it is failing to make progress. Kswapd throttles if
too many pages are under writeback and marked for immediate reclaim.
This patch explicitly throttles if reclaim is failing to make progress.
[vbabka@xxxxxxx: Remove redundant code]
Link: https://lkml.kernel.org/r/20211019090108.25501-4-mgorman@xxxxxxxxxxxxxxxxxxx
Signed-off-by: Mel Gorman <mgorman@xxxxxxxxxxxxxxxxxxx>
Acked-by: Vlastimil Babka <vbabka@xxxxxxx>
Cc: Andreas Dilger <adilger.kernel@xxxxxxxxx>
Cc: "Darrick J . Wong" <djwong@xxxxxxxxxx>
Cc: Dave Chinner <david@xxxxxxxxxxxxx>
Cc: Hillf Danton <hdanton@xxxxxxxx>
Cc: Johannes Weiner <hannes@xxxxxxxxxxx>
Cc: Jonathan Corbet <corbet@xxxxxxx>
Cc: Matthew Wilcox <willy@xxxxxxxxxxxxx>
Cc: Michal Hocko <mhocko@xxxxxxxx>
Cc: NeilBrown <neilb@xxxxxxx>
Cc: Rik van Riel <riel@xxxxxxxxxxx>
Cc: "Theodore Ts'o" <tytso@xxxxxxx>
Cc: Yang Shi <shy828301@xxxxxxxxx>
Signed-off-by: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx>
---
include/linux/mmzone.h | 1 +
include/trace/events/vmscan.h | 4 +++-
mm/memcontrol.c | 10 +---------
mm/vmscan.c | 28 ++++++++++++++++++++++++++++
4 files changed, 33 insertions(+), 10 deletions(-)
--- a/include/linux/mmzone.h~mm-vmscan-throttle-reclaim-when-no-progress-is-being-made
+++ a/include/linux/mmzone.h
@@ -276,6 +276,7 @@ enum lru_list {
enum vmscan_throttle_state {
VMSCAN_THROTTLE_WRITEBACK,
VMSCAN_THROTTLE_ISOLATED,
+ VMSCAN_THROTTLE_NOPROGRESS,
NR_VMSCAN_THROTTLE,
};
--- a/include/trace/events/vmscan.h~mm-vmscan-throttle-reclaim-when-no-progress-is-being-made
+++ a/include/trace/events/vmscan.h
@@ -29,11 +29,13 @@
#define _VMSCAN_THROTTLE_WRITEBACK (1 << VMSCAN_THROTTLE_WRITEBACK)
#define _VMSCAN_THROTTLE_ISOLATED (1 << VMSCAN_THROTTLE_ISOLATED)
+#define _VMSCAN_THROTTLE_NOPROGRESS (1 << VMSCAN_THROTTLE_NOPROGRESS)
#define show_throttle_flags(flags) \
(flags) ? __print_flags(flags, "|", \
{_VMSCAN_THROTTLE_WRITEBACK, "VMSCAN_THROTTLE_WRITEBACK"}, \
- {_VMSCAN_THROTTLE_ISOLATED, "VMSCAN_THROTTLE_ISOLATED"} \
+ {_VMSCAN_THROTTLE_ISOLATED, "VMSCAN_THROTTLE_ISOLATED"}, \
+ {_VMSCAN_THROTTLE_NOPROGRESS, "VMSCAN_THROTTLE_NOPROGRESS"} \
) : "VMSCAN_THROTTLE_NONE"
--- a/mm/memcontrol.c~mm-vmscan-throttle-reclaim-when-no-progress-is-being-made
+++ a/mm/memcontrol.c
@@ -3489,19 +3489,11 @@ static int mem_cgroup_force_empty(struct
/* try to free all pages in this cgroup */
while (nr_retries && page_counter_read(&memcg->memory)) {
- int progress;
-
if (signal_pending(current))
return -EINTR;
- progress = try_to_free_mem_cgroup_pages(memcg, 1,
- GFP_KERNEL, true);
- if (!progress) {
+ if (!try_to_free_mem_cgroup_pages(memcg, 1, GFP_KERNEL, true))
nr_retries--;
- /* maybe some writeback is necessary */
- congestion_wait(BLK_RW_ASYNC, HZ/10);
- }
-
}
return 0;
--- a/mm/vmscan.c~mm-vmscan-throttle-reclaim-when-no-progress-is-being-made
+++ a/mm/vmscan.c
@@ -3329,6 +3329,33 @@ static inline bool compaction_ready(stru
return zone_watermark_ok_safe(zone, 0, watermark, sc->reclaim_idx);
}
+static void consider_reclaim_throttle(pg_data_t *pgdat, struct scan_control *sc)
+{
+ /* If reclaim is making progress, wake any throttled tasks. */
+ if (sc->nr_reclaimed) {
+ wait_queue_head_t *wqh;
+
+ wqh = &pgdat->reclaim_wait[VMSCAN_THROTTLE_NOPROGRESS];
+ if (waitqueue_active(wqh))
+ wake_up_all(wqh);
+
+ return;
+ }
+
+ /*
+ * Do not throttle kswapd on NOPROGRESS as it will throttle on
+ * VMSCAN_THROTTLE_WRITEBACK if there are too many pages under
+ * writeback and marked for immediate reclaim at the tail of
+ * the LRU.
+ */
+ if (current_is_kswapd())
+ return;
+
+ /* Throttle if making no progress at high prioities. */
+ if (sc->priority < DEF_PRIORITY - 2)
+ reclaim_throttle(pgdat, VMSCAN_THROTTLE_NOPROGRESS, HZ/10);
+}
+
/*
* This is the direct reclaim path, for page-allocating processes. We only
* try to reclaim pages from zones which will satisfy the caller's allocation
@@ -3413,6 +3440,7 @@ static void shrink_zones(struct zonelist
continue;
last_pgdat = zone->zone_pgdat;
shrink_node(zone->zone_pgdat, sc);
+ consider_reclaim_throttle(zone->zone_pgdat, sc);
}
/*
_
Patches currently in -mm which might be from mgorman@xxxxxxxxxxxxxxxxxxx are
mm-vmscan-throttle-reclaim-until-some-writeback-completes-if-congested.patch
mm-vmscan-throttle-reclaim-and-compaction-when-too-may-pages-are-isolated.patch
mm-vmscan-throttle-reclaim-when-no-progress-is-being-made.patch
mm-writeback-throttle-based-on-page-writeback-instead-of-congestion.patch
mm-page_alloc-remove-the-throttling-logic-from-the-page-allocator.patch
mm-vmscan-centralise-timeout-values-for-reclaim_throttle.patch
mm-vmscan-increase-the-timeout-if-page-reclaim-is-not-making-progress.patch
mm-vmscan-delay-waking-of-tasks-throttled-on-noprogress.patch
