Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S933560Ab0FRPQ0 (ORCPT ); Fri, 18 Jun 2010 11:16:26 -0400 Received: from mail-gw0-f46.google.com ([74.125.83.46]:37760 "EHLO mail-gw0-f46.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S932219Ab0FRPQZ (ORCPT ); Fri, 18 Jun 2010 11:16:25 -0400 DomainKey-Signature: a=rsa-sha1; c=nofws; d=gmail.com; s=gamma; h=mime-version:in-reply-to:references:date:message-id:subject:from:to :cc:content-type; b=EChBAVelFNMOh3OT9auAbfqy4CuIR9sifkxA0n07xXGhjyjkb/yKHldCIuHNJm5BKI N7lm0wCWsovsrAppnSPnC7/eJUfg21b23RHnSNWaufYzEIXKzRR8W3DmbuQzRl40nz47 Uym45OUYSD03pWPRGZWJQu4Z+oSU9eJFOs7d8= MIME-Version: 1.0 In-Reply-To: <20100618143532.GA10886@elte.hu> References: <1276334896-7075-1-git-send-email-ying.huang@intel.com> <20100612102558.GA4000@elte.hu> <4C15A5D1.1040104@jp.fujitsu.com> <20100618094838.GD23977@elte.hu> <20100618124551.GC7612@elte.hu> <20100618143532.GA10886@elte.hu> Date: Fri, 18 Jun 2010 23:16:23 +0800 Message-ID: Subject: Re: [RFC 1/3] Unified NMI delayed call mechanism From: huang ying To: Ingo Molnar Cc: Hidetoshi Seto , Huang Ying , "Fr??d??ric Weisbecker" , Don Zickus , Peter Zijlstra , "H. Peter Anvin" , linux-kernel@vger.kernel.org, Andi Kleen Content-Type: text/plain; charset=UTF-8 Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 2108 Lines: 44 On Fri, Jun 18, 2010 at 10:35 PM, Ingo Molnar wrote: > > * huang ying wrote: > >> On Fri, Jun 18, 2010 at 8:45 PM, Ingo Molnar wrote: >> >> >> [...] ??At least APEI will use NMI to report some hardware events (likely >> >> >> error) to kernel. ??So I suppose we will go to have a delayed call as an >> >> >> event handler for APEI. >> >> > >> >> > Yep, that makes sense. I wasnt arguing against the functionality itself, i >> >> > was arguing against the illogical layering that limits its utility. By >> >> > making it part of perf events it becomes a generic part of that framework >> >> > and can be used by anything that deals with events and uses that >> >> > framework. >> >> >> >> I think the the 'layering' in the patchset helps instead of 'limits' its >> >> utility. It is designed to be as general as possible, so that it can be used >> >> by both perf and other NMI users. Do you think so? >> > >> > What other NMI users do you mean? EDAC/MCE is going to go utilize events >> > as well (away from the horrible /dev/mcelog interface), the NMI watchdog >> > already did it and the perf tool obviously does as well. There's a few >> > leftovers like kcrash which isnt really event centric and i dont think it >> > needs to be converted. >> >> But why not just make it more general? It does not hurt anyone including >> perf. > > Because it's not actually more generic that way - just look at the code. It's > x86 specific, plus it ties it to NMI delivery while the concept of delayed > execution has nothing to do with NMIs. soft_irq is a delayed mechanism for IRQ, a self interrupt can be a delayed mechanism for NMI. If we can make soft_irq NMI-safe, we can use soft_irq as a backup of self interrupt (for systems without APIC and maybe for other architectures). Best Regards, Huang Ying -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/