From mboxrd@z Thu Jan 1 00:00:00 1970 From: Eric Dumazet Subject: Re: RPS patch questions Date: Wed, 25 Aug 2010 15:16:50 +0200 Message-ID: <1282742210.2487.277.camel@edumazet-laptop> References: Mime-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: QUOTED-PRINTABLE Cc: netdev@vger.kernel.org To: Lal Return-path: Received: from mail-ew0-f46.google.com ([209.85.215.46]:40751 "EHLO mail-ew0-f46.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1752337Ab0HYNQ4 (ORCPT ); Wed, 25 Aug 2010 09:16:56 -0400 Received: by ewy23 with SMTP id 23so216433ewy.19 for ; Wed, 25 Aug 2010 06:16:54 -0700 (PDT) In-Reply-To: Sender: netdev-owner@vger.kernel.org List-ID: Le mercredi 25 ao=C3=BBt 2010 =C3=A0 18:05 +0530, Lal a =C3=A9crit : > I am evaluating RPS patch from Tom Herbert. I have some questions > regarding this patch. >=20 > 1. Can __smp_call_function_single be called from bottom half handler? > I presume, yes. >=20 right. > 2. I am working on 2.6.21 kernel which have neither > __smp_call_function_single nor smp_call_function_single. I used > smp_call_function_single from some other kernel version but this too > can not be called from bottom half handler (just like > smp_call_function). Did somebody try to write such function for 2.6.2= 1 > (or older kernel) which can be called from bottom halves? 2.6.21 is too old for us ;) >=20 > 3. One option I've is to upgrade to 2.6.27 kernel which has > __smp_call_function_single. I see a comment that this function must > not be called with interrupt disabled. Does it mean it can be called > from bottom half handler? >=20 __smp_call_function_single must be called with hard irqs enabled. bottom half handlers (softirqs) do run with hard irqs enabled.