Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1761733AbXEOHi7 (ORCPT ); Tue, 15 May 2007 03:38:59 -0400 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S1755979AbXEOHix (ORCPT ); Tue, 15 May 2007 03:38:53 -0400 Received: from gate.crashing.org ([63.228.1.57]:49265 "EHLO gate.crashing.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1754908AbXEOHiw (ORCPT ); Tue, 15 May 2007 03:38:52 -0400 Subject: Re: [patch 4/4] powerpc 2.6.21-rt1: reduce scheduling latency by changing tlb flush size From: Benjamin Herrenschmidt To: Tsutomu OWA Cc: Arnd Bergmann , linuxppc-dev@ozlabs.org, Thomas Gleixner , mingo@elte.hu, linux-kernel@vger.kernel.org In-Reply-To: References: <1179125506.22481.297.camel@localhost.localdomain> <200705141640.02561.arnd@arndb.de> Content-Type: text/plain Date: Tue, 15 May 2007 17:38:27 +1000 Message-Id: <1179214707.32247.177.camel@localhost.localdomain> Mime-Version: 1.0 X-Mailer: Evolution 2.10.1 Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 856 Lines: 31 > + > +#ifdef CONFIG_PREEMPT_RT > + /* > + * Since flushing tlb needs expensive hypervisor call(s) on celleb, > + * always flush it on RT to reduce scheduling latency. > + */ > + if (machine_is(celleb)) { > + flush_tlb_pending(); > + return; > + } > +#endif /* CONFIG_PREEMPT_RT */ > + > if (i >= PPC64_TLB_BATCH_NR) > flush_tlb_pending(); > } Any reason to do that only on celleb ? :-) Also, we might want to still batch, though in smaller amount. Have you measured the time it takes ? We might want to modulate the amount based on wether we are using native hash tables or an hypervisor. Ben. - 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/