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Mon, 7 Aug 2023 18:14:11 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=k20201202; t=1691432051; bh=j3TEHYhp6hr1p4VgaxfK1CNIdkHjvCIlVn8A8sCNygc=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=RsA6daF5bcPewpGwMVJ+pZDL+hUHfxed8UM7SgW9lSMBVmJMILfjHj857J4tPXy8x L4vKHLfXxOKg5h0JwzqHZ8QdchW6QIzU0cGyYRySEm2QZpm3Kp247gT00UgSix9oN8 IBXzRbKFE+BGwGUBAHkJzaKLrNtDTPxEAHTCRzqMnPTHRdrH5rtpwF1fi9brT7fXaB FglMjHij54cZrpqJby/uVeabtdz7QFW5cd40rAJpHGviLKuZW7IbtVGUtFC+Scwlnu SG2lcOPiuZq6asjUXjEi/HwJ7m97pu74HH9QQH0/EtKfVdHuBCeE8zen9W6u0yKtcJ MzkremrskSpBQ== From: SeongJae Park To: Hyeongtak Ji Cc: sj@kernel.org, akpm@linux-foundation.org, damon@lists.linux.dev, linux-mm@kvack.org, linux-kernel@vger.kernel.org, Hyeongtak Ji Subject: Re: [PATCH] mm/damon: Prevent unnecessary age reset for regions Date: Mon, 7 Aug 2023 18:14:09 +0000 Message-Id: <20230807181409.97310-1-sj@kernel.org> X-Mailer: git-send-email 2.25.1 In-Reply-To: <1691401475-3796-1-git-send-email-hyeongtak.ji@gmail.com> References: MIME-Version: 1.0 Content-Transfer-Encoding: 8bit X-Rspamd-Server: rspam08 X-Rspamd-Queue-Id: 3734EC0014 X-Stat-Signature: 7hbgsutzammhan1gorbpmkprejfju6ac X-Rspam-User: X-HE-Tag: 1691432053-531464 X-HE-Meta: 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 bbZx70iD v8TvFQ0FP8eMqMfID2KlyUnvcUQQbPo8UN2Flw2M5HsilM0ci637EayLCDkq3FPN4VkJCBiMmPr3ETLUfeg4V8RYo/vNRuTVxpNWcg7jKtcdhN+xeHqqO3+h//ImDBpXzW9SD5TCSuL2+6qFL396f0Mbi40zVh/3JkskGZLSSlBIiucYFEskVuIYAeRR7Su4DaSTXT4TnRaaYp82yanBoMPjXEgNOWFRPypikWX5LKml0S/wDUajq1Z9vhct0qDvUGeWZbOurvqRgQu7iaetjh/VP/AklDvgtlymLKq4TozKbtYhuFc0+m6rDskEsDwcCE3ay0YvPvEuLOTcyckPsuT8n+ZXgDlJvjhfXltLJlOzUa+0m+lQUcymj1pTI+IJI1nC7AkNpi5Wk2CSI0ouskqaE3MnPWCfAoXuK8WyIKa4y1QA= X-Bogosity: Ham, tests=bogofilter, spamicity=0.000004, version=1.2.4 Sender: owner-linux-mm@kvack.org Precedence: bulk X-Loop: owner-majordomo@kvack.org List-ID: Hi Hyeongtak, Thank you for this patch! On Mon, 7 Aug 2023 18:44:35 +0900 Hyeongtak Ji wrote: > DAMON resets the age of each region after applying each scheme, > regardless of whether the scheme has been successfully applied. > > This patch adds a simple condition to prevent the age of regions from > being reset when schemes have not been actually applied. We consider applying the action as making a change to the region, and hence reset the age to zero. Even if the action was not completely applied, that might be enough to make some change to the region. The behavior is also to limit a scheme too repeatedly and frequently applied to a region. So, this is not a bug but an intended behavior, and I think this change might not what really necessary. Is there a specific use case that this change is needed? If so, I think we can think about extending the interface to support the case. Thanks, SJ > > Signed-off-by: Hyeongtak Ji > --- > mm/damon/core.c | 2 +- > 1 file changed, 1 insertion(+), 1 deletion(-) > > diff --git a/mm/damon/core.c b/mm/damon/core.c > index 91cff7f2997e..4044fcf18ac1 100644 > --- a/mm/damon/core.c > +++ b/mm/damon/core.c > @@ -908,7 +908,7 @@ static void damos_apply_scheme(struct damon_ctx *c, struct damon_target *t, > quota->charge_addr_from = r->ar.end + 1; > } > } > - if (s->action != DAMOS_STAT) > + if (s->action != DAMOS_STAT && sz_applied > 0) > r->age = 0; > > update_stat: > -- > 2.7.4 >