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Message-Id: <20250513100730.12664-13-byungchul@sk.com> Date: Tue, 13 May 2025 19:06:59 +0900 From: Byungchul Park <byungchul@...com> To: linux-kernel@...r.kernel.org Cc: kernel_team@...ynix.com, torvalds@...ux-foundation.org, damien.lemoal@...nsource.wdc.com, linux-ide@...r.kernel.org, adilger.kernel@...ger.ca, linux-ext4@...r.kernel.org, mingo@...hat.com, peterz@...radead.org, will@...nel.org, tglx@...utronix.de, rostedt@...dmis.org, joel@...lfernandes.org, sashal@...nel.org, daniel.vetter@...ll.ch, duyuyang@...il.com, johannes.berg@...el.com, tj@...nel.org, tytso@....edu, willy@...radead.org, david@...morbit.com, amir73il@...il.com, gregkh@...uxfoundation.org, kernel-team@....com, linux-mm@...ck.org, akpm@...ux-foundation.org, mhocko@...nel.org, minchan@...nel.org, hannes@...xchg.org, vdavydov.dev@...il.com, sj@...nel.org, jglisse@...hat.com, dennis@...nel.org, cl@...ux.com, penberg@...nel.org, rientjes@...gle.com, vbabka@...e.cz, ngupta@...are.org, linux-block@...r.kernel.org, josef@...icpanda.com, linux-fsdevel@...r.kernel.org, jack@...e.cz, jlayton@...nel.org, dan.j.williams@...el.com, hch@...radead.org, djwong@...nel.org, dri-devel@...ts.freedesktop.org, rodrigosiqueiramelo@...il.com, melissa.srw@...il.com, hamohammed.sa@...il.com, harry.yoo@...cle.com, chris.p.wilson@...el.com, gwan-gyeong.mun@...el.com, max.byungchul.park@...il.com, boqun.feng@...il.com, longman@...hat.com, yskelg@...il.com, yunseong.kim@...csson.com, yeoreum.yun@....com, netdev@...r.kernel.org, matthew.brost@...el.com, her0gyugyu@...il.com Subject: [PATCH v15 12/43] dept: record the latest one out of consecutive waits of the same class The current code records all the waits for later use to track relation between waits and events within each context. However, since the same class is handled the same way, it'd be okay to record only one on behalf of the others if they all have the same class. Even though it's the ideal to search the whole history buffer for that, since it'd cost too high, alternatively, let's keep the latest one when the same class'ed waits consecutively appear. Signed-off-by: Byungchul Park <byungchul@...com> --- kernel/dependency/dept.c | 21 ++++++++++++++++++++- 1 file changed, 20 insertions(+), 1 deletion(-) diff --git a/kernel/dependency/dept.c b/kernel/dependency/dept.c index fc1d9e8b28f9..211bafffc980 100644 --- a/kernel/dependency/dept.c +++ b/kernel/dependency/dept.c @@ -1485,9 +1485,28 @@ static struct dept_wait_hist *new_hist(void) return wh; } +static struct dept_wait_hist *last_hist(void) +{ + int pos_n = hist_pos_next(); + struct dept_wait_hist *wh_n = hist(pos_n); + + /* + * This is the first try. + */ + if (!pos_n && !wh_n->wait) + return NULL; + + return hist(pos_n + DEPT_MAX_WAIT_HIST - 1); +} + static void add_hist(struct dept_wait *w, unsigned int wg, unsigned int ctxt_id) { - struct dept_wait_hist *wh = new_hist(); + struct dept_wait_hist *wh; + + wh = last_hist(); + + if (!wh || wh->wait->class != w->class || wh->ctxt_id != ctxt_id) + wh = new_hist(); if (likely(wh->wait)) put_wait(wh->wait); -- 2.17.1
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