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 EE4ADC433F5 for ; Thu, 25 Nov 2021 07:49:38 +0000 (UTC) Received: by kanga.kvack.org (Postfix) id 0D10D6B0074; Thu, 25 Nov 2021 02:49:23 -0500 (EST) Received: by kanga.kvack.org (Postfix, from userid 40) id 0810E6B0075; Thu, 25 Nov 2021 02:49:23 -0500 (EST) X-Delivered-To: int-list-linux-mm@kvack.org Received: by kanga.kvack.org (Postfix, from userid 63042) id EB1F16B007B; Thu, 25 Nov 2021 02:49:22 -0500 (EST) X-Delivered-To: linux-mm@kvack.org Received: from forelay.hostedemail.com (smtprelay0131.hostedemail.com [216.40.44.131]) by kanga.kvack.org (Postfix) with ESMTP id DB4E16B0074 for ; Thu, 25 Nov 2021 02:49:22 -0500 (EST) Received: from smtpin31.hostedemail.com (10.5.19.251.rfc1918.com [10.5.19.251]) by forelay02.hostedemail.com (Postfix) with ESMTP id 9DD0A8E2FF for ; Thu, 25 Nov 2021 07:49:12 +0000 (UTC) X-FDA: 78846676944.31.C2B322B Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by imf13.hostedemail.com (Postfix) with ESMTP id 145BD104628B for ; Thu, 25 Nov 2021 07:49:08 +0000 (UTC) Received: by mail.kernel.org (Postfix) with ESMTPSA id BF29460FDA; Thu, 25 Nov 2021 07:49:10 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=k20201202; t=1637826551; bh=B7QA2luaH0UV4huYU5YUs8013qNIQPksoEF//pKOFTE=; h=From:To:Cc:Subject:Date:In-Reply-To:From; b=hF7eAFwfE+2RYL++qxXmK4oKzfVS/DMehoyOg+HqeL4UcxSHQTvHqrmNIIUaiMLbB P9Qgsmn1evzYJ5Ekk90+MLwqLQHY0/L8p7P8cMgkl81nNAJ0lInZHyebM+0d7x8u9M pQ1/+xRtCo2+cNpeC2kL651FnMXR6Jhca4kXssp1zd5E+gTlsR3WhvjtPn19YLM8La j8OPsHgEvXJgvraUGxtoBDNREW+OfVrurOHBzn7vHzpsuzP0kya2GMrV/ggxJYRxsD 4SowyXv5+8BWGvEqz3Utte4Zu+XUu0/s7HMlUICOLAZ1wENb7f4RD55FtFkZjQRvaE AhrGSXCxB9UBw== From: SeongJae Park To: Andrew Morton Cc: SeongJae Park , shakeelb@google.com, linux-mm@kvack.org, linux-kernel@vger.kernel.org, stable@vger.kernel.org Subject: Re: [PATCH] mm/damon/core: Avoid fake load reports due to uninterruptible sleeps Date: Thu, 25 Nov 2021 07:49:08 +0000 Message-Id: <20211125074908.14412-1-sj@kernel.org> X-Mailer: git-send-email 2.17.1 In-Reply-To: <20211124134210.36ae288d02fea0a95e69e2ff@linux-foundation.org> X-Stat-Signature: y11qsw4kx57nd1uzr47onxjezs95wirz X-Rspamd-Queue-Id: 145BD104628B X-Rspamd-Server: rspam07 Authentication-Results: imf13.hostedemail.com; dkim=pass header.d=kernel.org header.s=k20201202 header.b=hF7eAFwf; spf=pass (imf13.hostedemail.com: domain of sj@kernel.org designates 198.145.29.99 as permitted sender) smtp.mailfrom=sj@kernel.org; dmarc=pass (policy=none) header.from=kernel.org X-HE-Tag: 1637826548-591406 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: On Wed, 24 Nov 2021 13:42:10 -0800 Andrew Morton wrote: > On Wed, 24 Nov 2021 14:52:19 +0000 SeongJae Park wrote: > > > Because DAMON sleeps in uninterruptible mode, /proc/loadavg reports fake > > load while DAMON is turned on, though it is doing nothing. This can > > confuse users[1]. To avoid the case, this commit makes DAMON sleeps in > > idle mode. > > > > --- a/mm/damon/core.c > > +++ b/mm/damon/core.c > > @@ -12,6 +12,8 @@ > > #include > > #include > > #include > > +#include > > +#include > > #include > > #include > > > > @@ -976,12 +978,25 @@ static unsigned long damos_wmark_wait_us(struct damos *scheme) > > return 0; > > } > > > > +/* sleep for @usecs in idle mode */ > > +static void __sched damon_usleep_idle(unsigned long usecs) > > +{ > > + ktime_t exp = ktime_add_us(ktime_get(), usecs); > > + u64 delta = usecs * NSEC_PER_USEC / 100; /* allow 1% error */ > > + > > + for (;;) { > > + __set_current_state(TASK_IDLE); > > + if (!schedule_hrtimeout_range(&exp, delta, HRTIMER_MODE_ABS)) > > + break; > > + } > > +} > > Let's not copy-n-paste usleep_range() into damon code? > > A new usleep_idle_range() in kernel/time/timer.c seems like a > worthwhile addition. Perhaps usleep_idle_range() and usleep_range() > can be static inline wrappers against a new, more general function in > kernel/time/timer.c - usleep_range_state(min, max, state)? Makes sense, agreed. I will post next version soon. Thanks, SJ