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b=jaYer3UkU1XnKYfff4RTI5kdyEoXoydQ9Uq+hWH5QUV/6fm64O+SyKY6w6ncUO6km c/t8alJnoPITaNLCj6H+jafLoaNyVreEpXaR7luV87rWLQguNQvyv8X2O9jBeVcUpg Vy+26mUE7HSWj3mrNodWLmb2phg0BI9OPzd1UDIyVHE97cq8n0yqRTIDlY3OnC9D+L yUZiPvPWbJYYqLr6AKUYrOsu0S1ToFj+ewvRtBoXs4Uuk5G27EtO+rUD1O3XuUYQv5 s1464Z+iOs1zBIGgvFTMp7L2wTVcRaH8A+Iu0LhRJwbn/RT65spHtXg7DV//IsPZsk qInAFc8KCxg6A== From: Mike Snitzer To: Matthew Wilcox , Jan Kara , linux-mm@kvack.org, Christian Brauner , linux-fsdevel@vger.kernel.org Cc: Chuck Lever , Jeff Layton , linux-nfs@vger.kernel.org Subject: [PATCH v11 3/7] mm: expose WB_DONTCACHE_DIRTY in bdi debugfs stats Date: Tue, 10 Nov 2026 20:56:03 -0500 Message-ID: <20261111015607.46338-4-snitzer@kernel.org> X-Mailer: git-send-email 2.44.0 In-Reply-To: <20261111015607.46338-1-snitzer@kernel.org> References: <20261111015607.46338-1-snitzer@kernel.org> X-Archived-By: MIME-Version: 1.0 Content-Transfer-Encoding: 8bit X-Stat-Signature: de4h3j4w9jpd5f4sriffyzit97qsiit3 X-Rspamd-Queue-Id: 8DE7080004 X-Rspam-User: X-Rspamd-Server: rspam08 X-Spam-Status: No, score=-18.8 required=3.0 tests=BAYES_00,DKIMWL_WL_HIGH, DKIM_SIGNED,DKIM_VALID,DKIM_VALID_AU,HEADER_FROM_DIFFERENT_DOMAINS, INCLUDES_CR_TRAILER,INCLUDES_PATCH,MAILING_LIST_MULTI,SPF_HELO_PASS, SPF_PASS,USER_AGENT_GIT autolearn=ham autolearn_force=no version=4.0.1 X-HE-Tag: 1794362173-349037 X-HE-Meta: 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 yHVB8nKQ xvBFqwB+s1pTbT20m4Ahq90SAf3asJ2xtib3c9R/FxZH4ETPj+36Fp/8pK7VglEUwcROv3CH8u3qgS/Wib3USkaNLZhJW+ZAluGsbYZmbl8ZzrTS33pPSeUorNrrOwGM8qe1xs4ty2+n8O2+85Hozqn3qVF6cnx6RSNJ6sYDXl4gl47waKYamOVYybCIRnoKFSAJniWmsJUljsfcdza0AqE28XzDLutJX4iSTNcLRYyYhgv7oLNQJWdjTll9j73gV14QHXRXZbw/9N//qo2dwIUosUA== Sender: owner-linux-mm@kvack.org Precedence: bulk X-Loop: owner-majordomo@kvack.org List-ID: List-Subscribe: X-Spam-Checker-Version: SpamAssassin 4.0.1 (2024-03-26) on aws-us-west-2-korg-listserv-alma10-1 The per-bdi_writeback WB_DONTCACHE_DIRTY counter drives how much the flusher writes back in response to an IOCB_DONTCACHE kick, but it is not reported anywhere, so the DONTCACHE dirty backlog can only be inferred from MemFree/Cached movement. Report it as BdiDontcacheDirty in /sys/kernel/debug/bdi//stats and as WbDontcacheDirty in the per-wb stats, next to the Reclaimable line. Use wb_stat_sum() rather than wb_stat() to fold in the per-cpu batches: the flusher targets the summed value and small backlogs would otherwise read as zero. Fixes: 88d6f128d06d ("mm: track DONTCACHE dirty pages per bdi_writeback") Reviewed-by: Jeff Layton Signed-off-by: Mike Snitzer --- mm/backing-dev.c | 6 ++++++ 1 file changed, 6 insertions(+) diff --git a/mm/backing-dev.c b/mm/backing-dev.c index fad1495d3b200..a09c21759fb9f 100644 --- a/mm/backing-dev.c +++ b/mm/backing-dev.c @@ -46,6 +46,7 @@ struct wb_stats { unsigned long nr_dirty_time; unsigned long nr_writeback; unsigned long nr_reclaimable; + unsigned long nr_dontcache_dirty; unsigned long nr_dirtied; unsigned long nr_written; unsigned long dirty_thresh; @@ -78,6 +79,7 @@ static void collect_wb_stats(struct wb_stats *stats, stats->nr_writeback += wb_stat(wb, WB_WRITEBACK); stats->nr_reclaimable += wb_stat(wb, WB_RECLAIMABLE); + stats->nr_dontcache_dirty += wb_stat_sum(wb, WB_DONTCACHE_DIRTY); stats->nr_dirtied += wb_stat(wb, WB_DIRTIED); stats->nr_written += wb_stat(wb, WB_WRITTEN); stats->wb_thresh += wb_calc_thresh(wb, stats->dirty_thresh); @@ -125,6 +127,7 @@ static int bdi_debug_stats_show(struct seq_file *m, void *v) seq_printf(m, "BdiWriteback: %10lu kB\n" "BdiReclaimable: %10lu kB\n" + "BdiDontcacheDirty: %10lu kB\n" "BdiDirtyThresh: %10lu kB\n" "DirtyThresh: %10lu kB\n" "BackgroundThresh: %10lu kB\n" @@ -139,6 +142,7 @@ static int bdi_debug_stats_show(struct seq_file *m, void *v) "state: %10lx\n", K(stats.nr_writeback), K(stats.nr_reclaimable), + K(stats.nr_dontcache_dirty), K(stats.wb_thresh), K(dirty_thresh), K(background_thresh), @@ -163,6 +167,7 @@ static void wb_stats_show(struct seq_file *m, struct bdi_writeback *wb, "WbCgIno: %10lu\n" "WbWriteback: %10lu kB\n" "WbReclaimable: %10lu kB\n" + "WbDontcacheDirty: %10lu kB\n" "WbDirtyThresh: %10lu kB\n" "WbDirtied: %10lu kB\n" "WbWritten: %10lu kB\n" @@ -179,6 +184,7 @@ static void wb_stats_show(struct seq_file *m, struct bdi_writeback *wb, #endif K(stats->nr_writeback), K(stats->nr_reclaimable), + K(stats->nr_dontcache_dirty), K(stats->wb_thresh), K(stats->nr_dirtied), K(stats->nr_written), -- 2.52.0