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[95.203.7.38]) by smtp.gmail.com with ESMTPSA id 38308e7fff4ca-30344061e1bsm9781791fa.51.2024.12.16.07.41.37 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Mon, 16 Dec 2024 07:41:38 -0800 (PST) From: Uladzislau Rezki X-Google-Original-From: Uladzislau Rezki Date: Mon, 16 Dec 2024 16:41:35 +0100 To: Vlastimil Babka Cc: Uladzislau Rezki , linux-mm@kvack.org, "Paul E . McKenney" , Andrew Morton , RCU , LKML , Christoph Lameter , Pekka Enberg , David Rientjes , Joonsoo Kim , Roman Gushchin , Hyeonggon Yoo <42.hyeyoo@gmail.com>, Oleksiy Avramchenko Subject: Re: [PATCH v2 0/5] Move kvfree_rcu() into SLAB (v2) Message-ID: References: <20241212180208.274813-1-urezki@gmail.com> <17476947-d447-4de3-87bb-97d5f3c0497d@suse.cz> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: X-Stat-Signature: wwrg9y5c1c3ywme14iwc5hwny8mnt4be X-Rspam-User: X-Rspamd-Queue-Id: 46447180019 X-Rspamd-Server: rspam08 X-HE-Tag: 1734363696-761082 X-HE-Meta: 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 7g1OlOUH 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 X-Bogosity: Ham, tests=bogofilter, spamicity=0.025681, 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 Mon, Dec 16, 2024 at 03:20:44PM +0100, Vlastimil Babka wrote: > On 12/16/24 12:03, Uladzislau Rezki wrote: > > On Sun, Dec 15, 2024 at 06:30:02PM +0100, Vlastimil Babka wrote: > >> On 12/12/24 19:02, Uladzislau Rezki (Sony) wrote: > >> > Hello! > >> > > >> > This is v2. It is based on the Linux 6.13-rc2. The first version is > >> > here: > >> > > >> > https://lore.kernel.org/linux-mm/20241210164035.3391747-4-urezki@gmail.com/T/ > >> > > >> > The difference between v1 and v2 is that, the preparation process is > >> > done in original place instead and after that there is one final move. > >> > >> Looks good, will include in slab/for-next > >> > >> I think patch 5 should add more explanation to the commit message - the > >> subthread started by Christoph could provide content :) Can you summarize so > >> I can amend the commit log? > >> > > I will :) > > > >> Also how about a followup patch moving the rcu-tiny implementation of > >> kvfree_call_rcu()? > >> > > As, Paul already noted, it would make sense. Or just remove a tiny > > implementation. > > AFAICS tiny rcu is for !SMP systems. Do they benefit from the "full" > implementation with all the batching etc or would that be unnecessary overhead? > Yes, it is for a really small systems with low amount of memory. I see only one overhead it is about driving objects in pages. For a small system it can be critical because we allocate. >From the other hand, for a tiny variant we can modify the normal variant by bypassing batching logic, thus do not consume memory(for Tiny case) i.e. merge it to a normal kvfree_rcu() path. After that we do not depend on CONFIG_RCU_TINY option. Probably we need also to perform some adaptation of regular kvfree_rcu() for a single CPU system. -- Uladzislau Rezki