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[34.64.151.24]) by smtp.gmail.com with ESMTPSA id v7sm2172219pjk.37.2021.10.05.06.31.05 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Tue, 05 Oct 2021 06:31:06 -0700 (PDT) Date: Tue, 5 Oct 2021 13:31:02 +0000 From: Hyeonggon Yoo <42.hyeyoo@gmail.com> To: Vlastimil Babka Cc: David Rientjes , linux-mm@kvack.org, Christoph Lameter , Pekka Enberg , Joonsoo Kim , Andrew Morton , linux-kernel@vger.kernel.org Subject: Re: [QUESTION] is SLAB considered legacy and deprecated? Message-ID: <20211005133102.GB2760@kvm.asia-northeast3-a.c.our-ratio-313919.internal> References: <20210927090347.GA2533@linux.asia-northeast3-a.c.our-ratio-313919.internal> <8aa15f4b-71de-5283-5ebc-d8d1a323473d@suse.cz> <20210928111231.GA2596@linux.asia-northeast3-a.c.our-ratio-313919.internal> <20211003055928.GA7643@linux.asia-northeast3-a.c.our-ratio-313919.internal> <377a622-9a5e-37dc-8f8d-42ae124042b6@google.com> <20211004060109.GA2949@linux.asia-northeast3-a.c.our-ratio-313919.internal> <075fde61-8c28-25ec-0ec1-28b1bdea7c95@suse.cz> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <075fde61-8c28-25ec-0ec1-28b1bdea7c95@suse.cz> Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Mon, Oct 04, 2021 at 01:39:46PM +0200, Vlastimil Babka wrote: > On 10/4/21 08:01, Hyeonggon Yoo wrote: > > On Sun, Oct 03, 2021 at 06:25:29PM -0700, David Rientjes wrote: > >> I would disagree that SLAB isn't currently maintained, I think it's > >> actively maintained. > > > > I thought it was not actively maintained because most of patches were > > fixups and cleanups for years and as Vlastimil said, new features are > > Fixups and cleanups still count as "actively maintained". The opposite > case would be "nobody uses it because it was broken for years since > commit X and we only noticed now". > Yup, there seems I was differently using meaning of "actively maintained". > > only added to SLUB. development was focused on SLUB. > > > >> I think the general guidance is that changes for both allocators can still > >> be merged upstream if they show a significant win (improved performnace, > >> maintaining performance while reducing memory footprint, code hygiene, > >> etc) and there's no specific policy that we cannot make changes to > >> mm/slab.c. > > > > Good. > > > > I see things to improve in SLAB and want to improve it. > > I will appreciate if you review them. > > It would be great if your motivation started with "I prefer SLAB over > SLUB because X and Y but I need to improve Z", not just a theoretical > concern. > Thank you for advice. by making dumb patches I realized that , yeah, just a theoretical concern does not help. I should have more understanding on internals of slab allocators and on how their characteristics affect performance depending on situation. and most importantly I should have actual evidence of performance measurement. I'm sorry and Thank you for thinking about and answering my (somewhat dumb) questions. But I'm happy that I'm learning a lot from your feedback. > > Thanks, > > Hyeonggon > > >