The patch titled
Subject: mm/page-writeback.c: make changes of dirty_writeback_centisecs take effect immediately
has been added to the -mm tree. Its filename is
writeback-change-of-dirty_writeback_interval-takes-effect-immediately.patch
This patch should soon appear at
http://ozlabs.org/~akpm/mmots/broken-out/writeback-change-of-dirty_writeback_interval-takes-effect-immediately.patch
and later at
http://ozlabs.org/~akpm/mmotm/broken-out/writeback-change-of-dirty_writeback_interval-takes-effect-immediately.patch
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From: Yafang Shao <laoar.shao@xxxxxxxxx>
Subject: mm/page-writeback.c: make changes of dirty_writeback_centisecs take effect immediately
Two problems with /proc/sys/vm/dirty_writeback_centisecs:
- When the tunable is set to 0 (disable), writing a non-zero value
doesn't restart the flushing operations until the dirty background limit
is reached or sys_sync is executed or not enough free memory is
available or vmscan is triggered.
- When the tunable was set to one hour and is reset to one second, the
new setting will not take effect for up to one hour.
Kicking the flusher threads immediately fixes these issues.
Link: http://lkml.kernel.org/r/1507746016-15344-1-git-send-email-laoar.shao@xxxxxxxxx
Signed-off-by: Yafang Shao <laoar.shao@xxxxxxxxx>
Cc: Jan Kara <jack@xxxxxxx>
Cc: Jens Axboe <axboe@xxxxxxxxx>
Signed-off-by: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx>
---
mm/page-writeback.c | 15 +++++++++++++--
1 file changed, 13 insertions(+), 2 deletions(-)
diff -puN mm/page-writeback.c~writeback-change-of-dirty_writeback_interval-takes-effect-immediately mm/page-writeback.c
--- a/mm/page-writeback.c~writeback-change-of-dirty_writeback_interval-takes-effect-immediately
+++ a/mm/page-writeback.c
@@ -1974,8 +1974,19 @@ bool wb_over_bg_thresh(struct bdi_writeb
int dirty_writeback_centisecs_handler(struct ctl_table *table, int write,
void __user *buffer, size_t *length, loff_t *ppos)
{
- proc_dointvec(table, write, buffer, length, ppos);
- return 0;
+ int ret = proc_dointvec(table, write, buffer, length, ppos);
+
+ /*
+ * Writing 0 to dirty_writeback_interval will disable periodic writeback
+ * and a different non-zero value will wakeup the writeback threads.
+ * wb_wakeup_delayed() would be more appropriate, but it's a pain to
+ * iterate over all bdis and wbs.
+ * The reason we do this is to make the change take effect immediately.
+ */
+ if (!ret && write && dirty_writeback_interval &&
+ dirty_writeback_interval != old_interval)
+ wakeup_flusher_threads(WB_REASON_PERIODIC);
+ return ret;
}
#ifdef CONFIG_BLOCK
_
Patches currently in -mm which might be from laoar.shao@xxxxxxxxx are
mm-print-a-warning-once-the-vm-dirtiness-settings-is-illogical.patch
writeback-change-of-dirty_writeback_interval-takes-effect-immediately.patch
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