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 lists.ozlabs.org (lists.ozlabs.org [112.213.38.117]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.lore.kernel.org (Postfix) with ESMTPS id 7F45BC5479D for ; Wed, 11 Jan 2023 17:05:53 +0000 (UTC) Received: from boromir.ozlabs.org (localhost [IPv6:::1]) by lists.ozlabs.org (Postfix) with ESMTP id 4NsYwb5x6Nz3cgw for ; Thu, 12 Jan 2023 04:05:51 +1100 (AEDT) Authentication-Results: lists.ozlabs.org; dkim=fail reason="signature verification failed" (2048-bit key; unprotected) header.d=google.com header.i=@google.com header.a=rsa-sha256 header.s=20210112 header.b=mNAGtaf8; dkim-atps=neutral Authentication-Results: lists.ozlabs.org; spf=pass (sender SPF authorized) smtp.mailfrom=google.com (client-ip=2607:f8b0:4864:20::b31; helo=mail-yb1-xb31.google.com; envelope-from=surenb@google.com; 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a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20210112; h=cc:to:subject:message-id:date:from:in-reply-to:references :mime-version:x-gm-message-state:from:to:cc:subject:date:message-id :reply-to; bh=LTJYmIxK7HXmivC0K3EGms7i6vie+YSU0ogRPhLAOWY=; b=LO7CON9mK2+t5qGi38pbCJWGgqWwEm5uip5pP7QrkwgckKy326YJ2ONOuaPm2XrZr9 d4D8BQmmvsCpDVs9+ZAOGPeIHodWbmWRznvJs0KziGiyKeW4QK2D459fZVSrSqBVHSZg c2062OJC/BgtSTmZzpt56pxOUF+X2tuB7KJP45yWwjZego8ehi5mAJkkP25SjbK7j2Li iBtui3enkqwFVCWaJCXTgrBqNRJDF4wKDwb1vwwJfwb8mdpib8Ogr2J1ax/ZpsXJPamK YkwHIIm4B1Bb8UCBDKjjKT0MvcsHWkx3qYupyt1acIm4q79/yK5HYeUTj+ByhM2WD80D cnoQ== X-Gm-Message-State: AFqh2kpvRMDRQeY/y+soIcMnx/mrBHs1u4P14pTlGB7t3Tx7icfMhKM+ NywFI2Bd7d5ad/rDEvBTIuq+p5G6jJdeKpt+BpMZIg== X-Google-Smtp-Source: AMrXdXuT2tWUr2Hd/aaxX3TJlatyg89hpnEY3Qn0fpRBzhAdGcwVITlGCP7wKe7gcAbYlKYD+1hcbSYSMwXYBplkZ8k= X-Received: by 2002:a25:1388:0:b0:7b8:6d00:ef23 with SMTP id 130-20020a251388000000b007b86d00ef23mr2129455ybt.119.1673456692551; Wed, 11 Jan 2023 09:04:52 -0800 (PST) MIME-Version: 1.0 References: <20230109205336.3665937-1-surenb@google.com> <20230109205336.3665937-9-surenb@google.com> <20230111001331.cxdeh52vvta6ok2p@offworld> <6be809f5554a4faaa22c287ba4224bd0@AcuMS.aculab.com> In-Reply-To: From: Suren Baghdasaryan Date: Wed, 11 Jan 2023 09:04:41 -0800 Message-ID: Subject: Re: [PATCH 08/41] mm: introduce CONFIG_PER_VMA_LOCK To: Michal Hocko Content-Type: text/plain; charset="UTF-8" X-BeenThere: linuxppc-dev@lists.ozlabs.org X-Mailman-Version: 2.1.29 Precedence: list List-Id: Linux on PowerPC Developers Mail List List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Cc: "michel@lespinasse.org" , "joelaf@google.com" , "songliubraving@fb.com" , "leewalsh@google.com" , "david@redhat.com" , "peterz@infradead.org" , "bigeasy@linutronix.de" , "peterx@redhat.com" , "dhowells@redhat.com" , "linux-mm@kvack.org" , "edumazet@google.com" , "jglisse@google.com" , "punit.agrawal@bytedance.com" , "arjunroy@google.com" , "paulmck@kernel.org" , "x86@kernel.org" , "hughd@google.com" , "willy@infradead.org" , Ingo Molnar , "gurua@google.com" , "laurent.dufour@fr.ibm.com" , "vbabka@suse.cz" , "rientjes@google.com" , "axelrasmussen@google.com" , "kernel-team@android.com" , "soheil@google.com" , "minchan@google.com" , "jannh@google.com" , "liam.howlett@oracle.com" , "shakeelb@google.com" , "luto@kernel.org" , "gthelen@google.com" , "ldufour@linux.ibm.com" , "linux-arm-kernel@lists.infradead.org" , "posk@google.com" , "lstoakes@gmail.com" , "peterjung1337@gmail.com" , "kent.overstreet@linux.dev" , "hughlynch@google.com" , "linux-kernel@vger.kernel.org" , David Laight , "hannes@cmpxchg.org" , "akpm@linux-foundation.org" , "t atashin@google.com" , "linuxppc-dev@lists.ozlabs.org" Errors-To: linuxppc-dev-bounces+linuxppc-dev=archiver.kernel.org@lists.ozlabs.org Sender: "Linuxppc-dev" On Wed, Jan 11, 2023 at 8:44 AM Michal Hocko wrote: > > On Wed 11-01-23 08:28:49, Suren Baghdasaryan wrote: > [...] > > Anyhow. Sounds like the overhead of the current design is small enough > > to remove CONFIG_PER_VMA_LOCK and let it depend only on architecture > > support? > > Yes. Further optimizations can be done on top. Let's not over optimize > at this stage. Sure, I won't optimize any further. Just to expand on your question. Original design would be problematic for embedded systems like Android. It notoriously has a high number of VMAs due to anonymous VMAs being named, which prevents them from merging. 2M per process increase would raise questions, therefore I felt the need for optimizing the memory overhead which is done in the last patch. Thanks for the feedback! > -- > Michal Hocko > SUSE Labs