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 X-Spam-Level: X-Spam-Status: No, score=-2.3 required=3.0 tests=HEADER_FROM_DIFFERENT_DOMAINS, MAILING_LIST_MULTI,SPF_HELO_NONE,SPF_PASS,USER_AGENT_SANE_1 autolearn=no autolearn_force=no version=3.4.0 Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id D8387C3A59F for ; Thu, 29 Aug 2019 15:27:29 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id AB2FC2077B for ; Thu, 29 Aug 2019 15:27:29 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1727794AbfH2P12 (ORCPT ); Thu, 29 Aug 2019 11:27:28 -0400 Received: from youngberry.canonical.com ([91.189.89.112]:52826 "EHLO youngberry.canonical.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1726739AbfH2P12 (ORCPT ); Thu, 29 Aug 2019 11:27:28 -0400 Received: from [213.220.153.21] (helo=wittgenstein) by youngberry.canonical.com with esmtpsa (TLS1.0:RSA_AES_256_CBC_SHA1:32) (Exim 4.76) (envelope-from ) id 1i3MKZ-00031b-0r; Thu, 29 Aug 2019 15:27:23 +0000 Date: Thu, 29 Aug 2019 17:27:22 +0200 From: Christian Brauner To: Joel Fernandes Cc: Greg KH , Peikan Tsai , arve@android.com, tkjos@android.com, maco@android.com, devel@driverdev.osuosl.org, linux-kernel@vger.kernel.org Subject: Re: [PATCH] binder: Use kmem_cache for binder_thread Message-ID: <20190829152721.ttsyfwaeygmwmcu7@wittgenstein> References: <20190829054953.GA18328@mark-All-Series> <20190829064229.GA30423@kroah.com> <20190829135359.GB63638@google.com> MIME-Version: 1.0 Content-Type: text/plain; charset=utf-8 Content-Disposition: inline In-Reply-To: <20190829135359.GB63638@google.com> User-Agent: NeoMutt/20180716 Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Thu, Aug 29, 2019 at 09:53:59AM -0400, Joel Fernandes wrote: > On Thu, Aug 29, 2019 at 08:42:29AM +0200, Greg KH wrote: > > On Thu, Aug 29, 2019 at 01:49:53PM +0800, Peikan Tsai wrote: > [snip] > > > The allocated size for each binder_thread is 512 bytes by kzalloc. > > > Because the size of binder_thread is fixed and it's only 304 bytes. > > > It will save 208 bytes per binder_thread when use create a kmem_cache > > > for the binder_thread. > > > > Are you _sure_ it really will save that much memory? You want to do > > allocations based on a nice alignment for lots of good reasons, > > especially for something that needs quick accesses. > > Alignment can be done for slab allocations, kmem_cache_create() takes an > align argument. I am not sure what the default alignment of objects is > though (probably no default alignment). What is an optimal alignment in your > view? Probably SLAB_HWCACHE_ALIGN would make most sense. > > > Did you test your change on a system that relies on binder and find any > > speed improvement or decrease, and any actual memory savings? > > > > If so, can you post your results? > > That's certainly worth it and I thought of asking for the same, but spoke too > soon! Yeah, it'd be interesting to see what difference this actually makes. Christian