From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org Received: from kanga.kvack.org (kanga.kvack.org [205.233.56.17]) by smtp.lore.kernel.org (Postfix) with ESMTP id B62E0C87FD3 for ; Wed, 6 Aug 2025 19:09:17 +0000 (UTC) Received: by kanga.kvack.org (Postfix) id 4679D6B0099; Wed, 6 Aug 2025 15:09:17 -0400 (EDT) Received: by kanga.kvack.org (Postfix, from userid 40) id 4185D6B009A; Wed, 6 Aug 2025 15:09:17 -0400 (EDT) X-Delivered-To: int-list-linux-mm@kvack.org Received: by kanga.kvack.org (Postfix, from userid 63042) id 3552E6B009D; Wed, 6 Aug 2025 15:09:17 -0400 (EDT) X-Delivered-To: linux-mm@kvack.org Received: from relay.hostedemail.com (smtprelay0010.hostedemail.com [216.40.44.10]) by kanga.kvack.org (Postfix) with ESMTP id 281EC6B0099 for ; Wed, 6 Aug 2025 15:09:17 -0400 (EDT) Received: from smtpin03.hostedemail.com (a10.router.float.18 [10.200.18.1]) by unirelay07.hostedemail.com (Postfix) with ESMTP id D77C61605C7 for ; Wed, 6 Aug 2025 19:09:16 +0000 (UTC) X-FDA: 83747270712.03.4780562 Received: from sea.source.kernel.org (sea.source.kernel.org [172.234.252.31]) by imf27.hostedemail.com (Postfix) with ESMTP id 1CC2140006 for ; Wed, 6 Aug 2025 19:09:14 +0000 (UTC) Authentication-Results: imf27.hostedemail.com; dkim=pass header.d=kernel.org header.s=k20201202 header.b=FhlIJ6sW; dmarc=pass (policy=quarantine) header.from=kernel.org; spf=pass (imf27.hostedemail.com: domain of sj@kernel.org designates 172.234.252.31 as permitted sender) smtp.mailfrom=sj@kernel.org ARC-Seal: i=1; s=arc-20220608; d=hostedemail.com; t=1754507355; a=rsa-sha256; cv=none; b=FpUn11bbaIYV0u5kgXJBNawQmpzxHKlT3LcO3nO/YWI1nuzuBwv/VrPZOtuIlh8uQhOWHX N03cQrFu2rAFE4TnUcQti0UDZ/mJzEG+V2WRsHCZS4hsjJOqW/+adYfdzXjCA94qbLICmd drzchJ9aGEUHs5PMTQvv6/gNnmv0M9U= ARC-Authentication-Results: i=1; imf27.hostedemail.com; dkim=pass header.d=kernel.org header.s=k20201202 header.b=FhlIJ6sW; dmarc=pass (policy=quarantine) header.from=kernel.org; spf=pass (imf27.hostedemail.com: domain of sj@kernel.org designates 172.234.252.31 as permitted sender) smtp.mailfrom=sj@kernel.org ARC-Message-Signature: i=1; a=rsa-sha256; c=relaxed/relaxed; d=hostedemail.com; s=arc-20220608; t=1754507355; h=from:from:sender:reply-to:subject:subject:date:date: message-id:message-id:to:to:cc:cc:mime-version:mime-version: content-type:content-transfer-encoding:content-transfer-encoding: in-reply-to:in-reply-to:references:references:dkim-signature; bh=63eNjk9Vetf2teryJZKtr18Ly2dXmnP2M/BHPl2bI04=; b=10aW83yqX0EyZQXRRe7NpYp8pS1pJGiXi3Ac49cFPY4wN61HHZ9wKwjw2crZHdTn3Owxo0 kRj13Wunrb2SoQppooWIrgPzjhiRfE0Q1eFEYOhTT0Sv1mPOo6lZj1zaaDPjK08IbFQC+a r42rhyhCFI3ewn/FgmqKMtdsY/UeKJo= Received: from smtp.kernel.org (transwarp.subspace.kernel.org [100.75.92.58]) by sea.source.kernel.org (Postfix) with ESMTP id 116E544AC0; Wed, 6 Aug 2025 19:09:14 +0000 (UTC) Received: by smtp.kernel.org (Postfix) with ESMTPSA id BEA30C4CEE7; Wed, 6 Aug 2025 19:09:13 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=k20201202; t=1754507353; bh=7N8Q4W4P+6iSheRgtygd3ecelGl8Z6De2VbO2stv2v0=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=FhlIJ6sWU67KGuHY4kg17vJ/xHLHncT5RcqKqgfAAe4wgP59od2t0gwdpxQumJOoq 9FLbkdA0zzJGKjl/NSUua4bMyJ2vlRBzXGWP9iJr3FUEx7JJBzkJYgxIRV9SA2QI1G I1cpET67sPVAjwOcOAKzdVYFez0zluQNS8G/x/f7MYajF8en2fyD4whBiYXse9C7Aj Rs1CNnkUaqX6eJIIrBIcyYtCFTgM0bmtyYHYHQ1ugpoexU1dyGSOzbA0Mbi2UVUE4Y lqECCF46lRHcG9QgxkRQ4YS6W624J7vb0CwvixlUS+Vw7Cd5lzooPLUCfpR8dHmatx gFp5NnkXjDd8g== From: SeongJae Park To: Bijan Tabatabai Cc: SeongJae Park , damon@lists.linux.dev, linux-mm@kvack.org, linux-kernel@vger.kernel.org, Andrew Morton , Bijan Tabatabai Subject: Re: [PATCH] mm/damon/core: skip needless update of next_{aggregation,ops_update}_sis Date: Wed, 6 Aug 2025 12:09:10 -0700 Message-Id: <20250806190911.49728-1-sj@kernel.org> X-Mailer: git-send-email 2.39.5 In-Reply-To: <20250806164316.5728-1-bijan311@gmail.com> References: MIME-Version: 1.0 Content-Transfer-Encoding: 8bit X-Stat-Signature: hzddfbrjmzta91unjj96kikns4yzhpcb X-Rspam-User: X-Rspamd-Queue-Id: 1CC2140006 X-Rspamd-Server: rspam02 X-HE-Tag: 1754507354-182374 X-HE-Meta: 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 NMJcJwkG Z1UCrrdlPn++U4QM7xS8MUSzygP74yQSeDpoFlqEpdpto2RSoHrdP4TrfL8aYVconkrG7XlttCFu9htrxoepr/iWc1e6kJn2YtfHZlirN2pVXcNBujvgqeJg8m44t07UOUoO/OYGvhPDti4apQaONVxcUIdbpRXnvo1WjBlUE0eVrSVgH2H1dGrn6FRHjG6IE5O4fEPGcLGd5sxGNo+EdlIO3VipHrrfm09mEHAgtXoH1M6qJ+rj3iz4pCdmK9Bg/XDPLIm1pC4l0hVorZIL7Z8AE2Dfy8gdfJlxKzEWGva4E30bMtV/00WulF/y7UP00cXIiyDyy8/P/7H4Zcka5YZYogAunQC9LRdLlt+V6+D4HqTs= X-Bogosity: Ham, tests=bogofilter, spamicity=0.000000, version=1.2.4 Sender: owner-linux-mm@kvack.org Precedence: bulk X-Loop: owner-majordomo@kvack.org List-ID: List-Subscribe: List-Unsubscribe: Hi Bijan, On Wed, 6 Aug 2025 11:43:16 -0500 Bijan Tabatabai wrote: > From: Bijan Tabatabai > > In damon_set_attrs(), ctx->next_{aggregation,ops_update}_sis would be > reset, even if the sample interval, aggregation interval, or ops update > interval were not changed. If damon_set_attrs() is called relatively > frequently, such as by frequent "commit" operations, aggregation and ops > update operations could be needlessly delayed. > > This patch avoids this by only updating next_{aggregation,ops_update}_sis > if the relevant intervals were changed. > > Cc: Bijan Tabatabai > Signed-off-by: Bijan Tabatabai > --- > This patch came from discussions in [1]. > > [1] https://lore.kernel.org/all/20250805162022.4920-1-bijan311@gmail.com/ Thank you for sending this patch as we discussed on the thread! > --- > mm/damon/core.c | 16 ++++++++++++---- > 1 file changed, 12 insertions(+), 4 deletions(-) > > diff --git a/mm/damon/core.c b/mm/damon/core.c > index 6a2fe1f2c952..1c3d8b92257c 100644 > --- a/mm/damon/core.c > +++ b/mm/damon/core.c > @@ -693,6 +693,12 @@ int damon_set_attrs(struct damon_ctx *ctx, struct damon_attrs *attrs) > unsigned long sample_interval = attrs->sample_interval ? > attrs->sample_interval : 1; > struct damos *s; > + bool sample_interval_changed = ctx->attrs.sample_interval != > + attrs->sample_interval; > + bool aggr_interval_changed = ctx->attrs.aggr_interval != > + attrs->aggr_interval; > + bool ops_update_interval_changed = ctx->attrs.ops_update_interval != > + attrs->ops_update_interval; > bool aggregating = ctx->passed_sample_intervals < > ctx->next_aggregation_sis; > > @@ -710,10 +716,12 @@ int damon_set_attrs(struct damon_ctx *ctx, struct damon_attrs *attrs) > if (!attrs->aggr_samples) > attrs->aggr_samples = attrs->aggr_interval / sample_interval; > > - ctx->next_aggregation_sis = ctx->passed_sample_intervals + > - attrs->aggr_interval / sample_interval; > - ctx->next_ops_update_sis = ctx->passed_sample_intervals + > - attrs->ops_update_interval / sample_interval; > + if (sample_interval_changed || aggr_interval_changed) > + ctx->next_aggregation_sis = ctx->passed_sample_intervals + > + attrs->aggr_interval / sample_interval; > + if (sample_interval_changed || ops_update_interval_changed) > + ctx->next_ops_update_sis = ctx->passed_sample_intervals + > + attrs->ops_update_interval / sample_interval; > > damon_update_monitoring_results(ctx, attrs, aggregating); > ctx->attrs = *attrs; Long story short, this (original) code is bit complicated and hence I suggest to make this change less optimum but simpler. damon_update_monitoring_results() assumes it is called only just after next_{aggr,ops_update}_sis are updated. And the assumption is important for the pseudo-moving-sum access frequency maintenance. As a result, this can make the monitoring results temporarily corrupted, and splat warning once. Please refer to commit 591c4c78be063 ("mm/damon/core: warn and fix nr_accesses[_bp] corruption") or the patch thread[1] if you want more details. Also damon_set_attrs() is called not only from commit situation. So I think this maybe not an ideal part to modify. What about modifying damon_commit_ctx() to check if new and old damon_ctx->attrs are entirely same, and skip calling damon_set_attrs() in the case? Doing the entire damon_attrs comparison might be suboptimum, but would make the change simpler. I assume the suboptimum comparison is not a real problem for your use case, so I think that could be a good tradeoff? Also, I realize the moving sum access frequencies maintenance and damon_set_attrs() are not well documented and organized. I will try to make those better cleaned up and documented. [1] https://lkml.kernel.org/r/20250513002715.40126-2-sj@kernel.org Thanks, SJ > -- > 2.43.0