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Thu, 30 Nov 2023 13:37:16 -0800 (PST) Received: from dschatzberg-fedora-PF3DHTBV ([2620:10d:c091:500::7:5fb0]) by smtp.gmail.com with ESMTPSA id bj16-20020a05620a191000b0077d66e5b2e6sm855589qkb.3.2023.11.30.13.37.15 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Thu, 30 Nov 2023 13:37:16 -0800 (PST) Date: Thu, 30 Nov 2023 16:37:13 -0500 From: Dan Schatzberg To: Shakeel Butt Cc: Johannes Weiner , Michal Hocko , Roman Gushchin , Yosry Ahmed , Huan Yang , linux-kernel@vger.kernel.org, cgroups@vger.kernel.org, linux-mm@kvack.org, Muchun Song , Andrew Morton , David Hildenbrand , Matthew Wilcox , Huang Ying , Kefeng Wang , Peter Xu , "Vishal Moola (Oracle)" , Yue Zhao , Hugh Dickins Subject: Re: [PATCH 0/1] Add swappiness argument to memory.reclaim Message-ID: References: <20231130153658.527556-1-schatzberg.dan@gmail.com> <20231130165642.GA386439@cmpxchg.org> MIME-Version: 1.0 Content-Type: text/plain; charset=utf-8 Content-Disposition: inline Content-Transfer-Encoding: 8bit In-Reply-To: X-Rspam-User: X-Stat-Signature: 663ej4p1wmbqescuy3affg3hj3c975rz X-Rspamd-Server: rspam07 X-Rspamd-Queue-Id: EEC5C40022 X-HE-Tag: 1701380237-379817 X-HE-Meta: U2FsdGVkX18J6az4KPiIbS7nSMgNqOOJa4X53O4TxnyRP8Odx+uXJbIbcYg0XzCYx/qjrDJGA/jtMbAcyJvbbPl+EFxa3VS+fXF/3Gyl2srkEIXpZeA6ATMl0lyg4phi/HPNeM1dggLKnTjD97BGdrpr/TOeKuGLJ35Zh1zXcZqJ++GxVnBs/rQtjUhqdUYcYDu2Z+IrrCsDgkMllPHit3v1Mv6yPIYf1qDcUoViDxx91G6jmbWf1BYFuKaQZKtOwQC4ds9+MNsYceffc5p06PB3jlr9D8cRS4ThQ3FYM7qZC+5YtmjGaVWZNXkeRKDJLa9v2FwDftmCD1NEo1kQzgCTsdtqUYZ2UvwQWukS4Ro674FZPKK6XoDOkd+2pz2BBBFEWZf38stIoC7xyk9PNi8+RlscGjLdjflaHbyzGxHzpApmQe31zbA/9jynljplHYRmW98C4FzeruNwT2nkMYHYPZc2ntNdWPKiTKYr4AOdZBYlReLvqxjcFAeYwOee88tvTiLS/rV+cc9zttCsj491SSmi9+d3cYzYGXXuCgknPssthg0y3aNw542xBBy3vLXprlZb4SdYahCOc1F29H9WhGyXWeysuBB+8dmwK7JFVA/gnc33r2kJZTTMkIb5U4VifFPi/fAXpGAMXXEqUBUAWKZN4jlUTjGEcIsc/53RAWc8nEdM/X1UApsemvR/txTpljI3wnmIqvtd/Roko4JB9/3UgQjxyMRe3K2fQ+KFBLQRgSdpj4TmJh5mLtynDrGr/yjx2MB7R6N1ir9eBzJc4UokUWIT7UOWxsh1lhTIEVdmnri5bOYLFNyZqOiCc4Cv2abEiMUKVORQoyqhAh+qNF0Mixedwd6dqbC6JdBmhgcPK0wEqr25kXbZeAHiftjV+vIP9NMgLUXyjv0jUXuLNl0edzsuqrEDpfVC2UmNjPrDwFBCAZbOKd14691IM20Vos+ssSqP5bYcQpJ FbVDCgrk IieHH5l+DkANTY16nUMXtkF0fSR/P3p63+V/1YxjZdRotV/+hDT35m1n9MnpGjnQjTcGliDBksMBzNTmQVCvUKdXJ254+WYv2Cb91pdkKliG6IRSCTbKz1a5kG4bC5uuIjNXU65WlSXKLjm/9NjJ/wd9p/f8eExssG4o5njKroMGGuel2g3PbOIr7csHmFrEQkGeoRmsgAMWFkVpRfNDGUbRZYx9KrGwyWzz+kgsdhM6GyVO6417+5+7ErD6GDbSfL2mB0icBi2MUzkHnE2PE6kRfO+rKD5hmTOo7uMfjPq/SFXCL+TnmXmsvWxtheW78hdJdbqRA33/WnaCIK10xN9ZuWoAsOvAy/1xaykCEXYhG2UxPX13aT1p1SEBSC3LcfHKunvQ/qh5h1BfvbNu5RDkF30EqS8Mm6iQb1fUZLT99vqjxgXlKd/QDZShhj2SDbjn21PvV3RtbQ+X5xdcTynsB5oqgGZrOouT1T/1lPdsy5/KzvPOz30z084EooI30e4gGFfegFOUt/+iUxyFYUfj6J8VA1IyJrR3dB2Vp1ogO7raBCthpYlSb0YMmmMna/V12aB4ZmU9FpsO1v7jGRaXw90zR7FUJiiAi X-Bogosity: Ham, tests=bogofilter, spamicity=0.000016, version=1.2.4 Sender: owner-linux-mm@kvack.org Precedence: bulk X-Loop: owner-majordomo@kvack.org List-ID: List-Subscribe: List-Unsubscribe: On Thu, Nov 30, 2023 at 12:30:27PM -0800, Shakeel Butt wrote: > On Thu, Nov 30, 2023 at 11:47 AM Dan Schatzberg > wrote: > > > > On Thu, Nov 30, 2023 at 11:56:42AM -0500, Johannes Weiner wrote: > > > [...] > > > So I wouldn't say it's merely a reclaim hint. It controls a very > > > concrete and influential factor in VM decision making. And since the > > > global swappiness is long-established ABI, I don't expect its meaning > > > to change significantly any time soon. > > > > I want to add to this last point. While swappiness does not have > > terribly well-defined semantics - it is the (only?) existing mechanism > > to control balance between anon and file reclaim. I'm merely > > advocating for the ability to adjust swappiness during proactive > > reclaim separately from reactive reclaim. To what degree the behavior > > and semantics of swappiness change is a bit orthogonal here. > > Let me ask my question in this chain as it might have been missed: > > Whatever the semantics of swappiness are (including the edge cases > like no swap, file_is_tiny, trim cache), should the reclaim code treat > the global swappiness and user-provided swappiness differently? I can't think of any reason why we would want swappiness interpreted differently if it's provided at proactive reclaim time vs globally. Did you have something in mind here?