From 81468bbb0dd07e51109e215af0b17fdbd40d6160 Mon Sep 17 00:00:00 2001 From: Yafang Shao Date: Sat, 14 Oct 2017 16:38:27 +0800 Subject: [PATCH] mm/page-writeback.c: make changes of dirty_writeback_centisecs take effect immediately This patch is the followup of the prvious patch: [writeback: schedule periodic writeback with sysctl]. There's another issue to fix. For example, - 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 it. Cc: Jens Axboe Cc: Jan Kara Cc: Andrew Morton Signed-off-by: Yafang Shao Signed-off-by: Jens Axboe --- mm/page-writeback.c | 11 ++++++++++- 1 file changed, 10 insertions(+), 1 deletion(-) diff --git a/mm/page-writeback.c b/mm/page-writeback.c index 622a18c114caa..c518c845f2025 100644 --- a/mm/page-writeback.c +++ b/mm/page-writeback.c @@ -1976,7 +1976,16 @@ int dirty_writeback_centisecs_handler(struct ctl_table *table, int write, int ret; ret = proc_dointvec(table, write, buffer, length, ppos); - if (!ret && !old_interval && dirty_writeback_interval) + + /* + * 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; -- 2.39.5