From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1759579AbYG2OeZ (ORCPT ); Tue, 29 Jul 2008 10:34:25 -0400 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S1758207AbYG2OeP (ORCPT ); Tue, 29 Jul 2008 10:34:15 -0400 Received: from fg-out-1718.google.com ([72.14.220.154]:40015 "EHLO fg-out-1718.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1759485AbYG2OeK (ORCPT ); Tue, 29 Jul 2008 10:34:10 -0400 DomainKey-Signature: a=rsa-sha1; c=nofws; d=gmail.com; s=gamma; h=message-id:date:from:user-agent:mime-version:to:cc:subject :x-enigmail-version:content-type:content-transfer-encoding; b=RpG3jB3/RNlNpe1gGT72bZpvpccF0LMiNgMvsWXZ9rPK3MSNF3825o19NfKcd1YVIA hfkkeCS1HQ/tbUeE1R4mecwNgt/wjoneaEs3jn7t+/WLkUeZklhIStsn+QYdwkSOAM/k rlj0/KQRDvV/seS+48mJiJe+FkRXP5h1MGTaM= Message-ID: <488F2A65.2090405@gmail.com> Date: Tue, 29 Jul 2008 16:34:13 +0200 From: Jiri Slaby User-Agent: Thunderbird 2.0.0.16 (X11/20080720) MIME-Version: 1.0 To: Ingo Molnar CC: Mike Travis , Linux kernel mailing list Subject: cpu4096 + smp_affinity breakage X-Enigmail-Version: 0.95.6 Content-Type: text/plain; charset=UTF-8; format=flowed Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Hi, I see cpu4096 branches in -tip. Do you know about /proc/irq/*/*smp_affinity (irq_affinity_read_proc, default_affinity_read) breakage with NR_CPUS=4096? Reading by `cat' from those files fails due to bitmap sent out is about 1150 bytes, but cat provides only 1024B sized buffer. Can you think about any fix for this? Using file offset and utilize only portion of that buffer returned to the userspace will break atomicity I guess (does this matter?). If we get a snapshot, it would get old if some reader breaks up. And if we use per-reader buffer, we will be unable to free it. Any ideas? I think the same problem is for not-at-once-writes.