From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from mout.gmx.net (mout.gmx.net [212.227.15.18]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id D1D7B72 for ; Sun, 28 Nov 2021 18:38:59 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=gmx.net; s=badeba3b8450; t=1638124723; bh=rKAHtJtT/7cat6vBkBPLTPsYhFpRT2TD5/4AQ8wISI4=; h=X-UI-Sender-Class:Subject:From:To:Cc:Date:In-Reply-To:References; b=ScBuLgU2/5CvMymm+qb72tgAOi5S/qa7EB/4A7DOmDTtr2zFMnGe59WNdMHrOhQtx Sao8vXvfWZ6FSyzJZj9tG/r6shsGGoHIhd6Ux+VLnOlkxZtPgw+toFUzreDsuP31wL gRmCvpYm2LY0oErDIePNbEsuW5FIS6GxuITKZqjs= X-UI-Sender-Class: 01bb95c1-4bf8-414a-932a-4f6e2808ef9c Received: from homer.fritz.box ([185.221.150.210]) by mail.gmx.net (mrgmx004 [212.227.17.190]) with ESMTPSA (Nemesis) id 1MwfWa-1mfesS457q-00y8UY; Sun, 28 Nov 2021 19:38:43 +0100 Message-ID: <1c1835271e0ea093dd169d19038b477cf8563c32.camel@gmx.de> Subject: Re: [PATCH 1/1] mm: vmscan: Reduce throttling due to a failure to make progress From: Mike Galbraith To: Alexey Avramov , Mel Gorman Cc: Andrew Morton , Michal Hocko , Vlastimil Babka , Rik van Riel , Darrick Wong , regressions@lists.linux.dev, Linux-fsdevel , Linux-MM , LKML Date: Sun, 28 Nov 2021 19:38:37 +0100 In-Reply-To: References: <20211125151853.8540-1-mgorman@techsingularity.net> <20211127011246.7a8ac7b8@mail.inbox.lv> <20211126165211.GL3366@techsingularity.net> <20211128042635.543a2d04@mail.inbox.lv> <252cd5acd9bf6588ec87ce02884925c737b6a8b7.camel@gmx.de> <941f378e1ea2b32cac0adee1e81637ab6d001f1e.camel@gmx.de> Content-Type: text/plain; charset="UTF-8" User-Agent: Evolution 3.42.1 Precedence: bulk X-Mailing-List: regressions@lists.linux.dev List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Transfer-Encoding: quoted-printable X-Provags-ID: V03:K1:PIpqMRP8LvoWi9ghl2L5TJcmjnh4OeK7+d9fYHakEFhoqsjKICx DGGEPb/LoF8lS2/v+mfJTarrfldby9gS/SC+oigwLdPDStD2y9Ol7l5Mj0gWa822s3mtlZ8 qE0U9WuBsMBUtufJ9GVSdcUKM3impPGS6ItlhVMxHWFAq8PXFA3L9gt+Xb+VwBxL0pzeqh6 6LAGfOvZv+qB7sY3bgNnA== X-Spam-Flag: NO X-UI-Out-Filterresults: notjunk:1;V03:K0:Auhalq6g+To=:ldnXkgH9wZk2YuKSYFqh7K 0IG4xJB7GWR2z5B8eoUPLASRRnCgD0HQj9ZjASTYKofRnZ19PRktYXGacA19ITgVn1blTvxel lOszevT7F57i3yE8nYBc2ohW96SMhieKgq04X+9saTKLffPD0aWJd9JCiSPD0DI5JAzJv0n9W pyFVRoH8d+L0hcivPnsYvNqddAwQXZG0OSloqClSkYk/Rd4B22w/uO+y5FnwjleFudOSnvDju iCS0edvp9mj/NmYGV2hsPDyF9HstXkM29NyJQTICnpsSV8o8OPXgsG379/QYPanpnaYcZxpYq HhOLMLVXWe8S7SvFB8SI+G4fGb9//iJg1FW1rBIQghYxa/qI4fSer5qoyBp+Xp1wZh8oU1IjM JrnEbjGdInMG1b//Yy+DAc6BIrJtKSFPx4CkE89AXH27G/Wsp48M9ASMbf4DBTTyMKB+6+n6z O70ArBMgejRy7YjJClzYdbUVVmKCMvV1oMKSXrMkGiI0DNw0AXn3HjKJs/1UcxBrSrbQgN9Cu KbmzM/C5lUK6gygY+7F30JPmch3BSjHa512/TZwRXGV41XnPGZQKguFgyQFpmKUjqEAxIFBHL 8rBw5xvtjlRp/IFXVzDLSLg+s5RkYdDQVc2ve48nz8zpu7cWDO0eLoCNgYFnIaORXNM6EbJio PzxR5Yai02KpeonCbVcybKbyH8aIbLwiLmf83mWUBWcVLbOj/oltcVa9+StxUjxMs9ZHTlN6I cIRUFFLf8cmo8CQB2dgOm20q3/H7yRDc0ARjYfSy36+/MlrzhvLYAiTW9OC2ubqHGguNUxrCM Ko5NDsNt7ZXjH8DcT5g1AWDtG3PB9NSpMe+cUgCu9ZQwcOEu4m+3BmphVabcuHOQgYdZf4yas liVyrAnP8w1xbHVJuJvCc3f7mK0iRjte7d0Zmbd28NmOR8Ico0KMP4ospoW4pbbdOG7a4eKRY MVCM9mn4Lo4VsnggWI04BJ6uB+tjQosXBnJFHIec9IT1+q2x69AwJpqVPiuF3sggxxnBkwhnd GG6c6IO4H9yTHlVvHYVj+kwWMWIUw+ZSMqsGhKFtJ8dOkSkOocr5X+ZKqFUK2/Y+o2X5fmY+N YE+UuiHSAcyDuk= On Sun, 2021-11-28 at 13:35 +0100, Mike Galbraith wrote: > > Bandaid likely just break the writeback bits all to pieces, but that's > ok, if breakage makes things work better, they need more breaking :) @@ -1048,6 +1050,10 @@ void reclaim_throttle(pg_data_t *pgdat, */ switch(reason) { case VMSCAN_THROTTLE_WRITEBACK: + if (!async_bdi_congested()) { + cond_resched(); + return; + } And indeed, that's the only THROTTLE_WRITEBACK path I've seen taken. Not pulling the plug made no difference to the tail /dev/zero test, leaving only the bits I swiped from defunct wait_iff_congested() as behavior delta cause. Actually sleeping there apparently stings. -Mike