From mboxrd@z Thu Jan 1 00:00:00 1970 Date: Wed, 26 Mar 2008 18:35:09 +0100 From: Ingo Molnar Subject: Re: [PATCH 06/10] x86: reduce memory and stack usage in intel_cacheinfo Message-ID: <20080326173508.GI20016@elte.hu> References: <20080325220650.835342000@polaris-admin.engr.sgi.com> <20080325220651.683748000@polaris-admin.engr.sgi.com> <20080326065023.GG18301@elte.hu> <47EA6EA3.1070609@sgi.com> <20080326171241.GC20016@elte.hu> <47EA87D8.8030305@zytor.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <47EA87D8.8030305@zytor.com> Sender: owner-linux-mm@kvack.org Return-Path: To: "H. Peter Anvin" Cc: Mike Travis , Andrew Morton , linux-mm@kvack.org, linux-kernel@vger.kernel.org, Thomas Gleixner , Ingo Molnar , Andi Kleen List-ID: * H. Peter Anvin wrote: > Ingo Molnar wrote: >>> The main goal was to avoid allocating 4096 bytes when only 32 would do >>> (characters needed to represent nr_cpu_ids cpus instead of NR_CPUS cpus.) >>> But I'll look at cleaning it up a bit more. It wouldn't have to be a >>> function if CHUNKSZ in cpumask_scnprintf() were visible (or a >>> non-changeable constant.) >> >> well, do we care about allocating 4096 bytes, as long as we also free it? >> It's not like we need to clear all the bytes or something. Am i missing >> something here? > > Well, 32 bytes fits on the stack, whereas 4096 bytes requires > allocating a page -- which means either taking the risk of failing or > blocking. Of course, we're doing this for output, which has the same > issue. hm, i thought this was all implemented via dynamic allocation already, within the cpumask_scnprintf function. But i see it doesnt do it - i guess a new call could be introduced, cpumask_scnprintf_ptr() which passes in a cpumask pointer and does dynamic allocation itself? Ingo -- To unsubscribe, send a message with 'unsubscribe linux-mm' in the body to majordomo@kvack.org. For more info on Linux MM, see: http://www.linux-mm.org/ . Don't email: email@kvack.org