Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1751554AbbEARs1 (ORCPT ); Fri, 1 May 2015 13:48:27 -0400 Received: from mail2-relais-roc.national.inria.fr ([192.134.164.83]:61522 "EHLO mail2-relais-roc.national.inria.fr" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1750963AbbEARsX (ORCPT ); Fri, 1 May 2015 13:48:23 -0400 X-IronPort-AV: E=Sophos;i="5.13,351,1427752800"; d="scan'208";a="138493281" Date: Fri, 1 May 2015 19:48:20 +0200 (CEST) From: Julia Lawall X-X-Sender: jll@localhost6.localdomain6 To: "Simmons, James A." cc: "'Julia Lawall'" , Oleg Drokin , "devel@driverdev.osuosl.org" , Greg Kroah-Hartman , "kernel-janitors@vger.kernel.org" , "linux-kernel@vger.kernel.org" , "HPDD-discuss@lists.01.org" Subject: RE: [HPDD-discuss] [PATCH 2/11] Staging: lustre: fld: Use kzalloc and kfree In-Reply-To: Message-ID: References: <1430495482-933-1-git-send-email-Julia.Lawall@lip6.fr> <1430495482-933-11-git-send-email-Julia.Lawall@lip6.fr> User-Agent: Alpine 2.02 (DEB 1266 2009-07-14) MIME-Version: 1.0 Content-Type: TEXT/PLAIN; charset=US-ASCII Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 1511 Lines: 29 On Fri, 1 May 2015, Simmons, James A. wrote: > >From: Julia Lawall > > > >Replace OBD_ALLOC, OBD_ALLOC_WAIT, OBD_ALLOC_PTR, and OBD_ALLOC_PTR_WAIT by > >kalloc/kcalloc, and OBD_FREE and OBD_FREE_PTR by kfree. > > Nak: James Simmons > > A simple replace will not work. The OBD_ALLOC and OBD_FREE functions allocate memory > anywhere from one page to 4MB in size. You can't use kmalloc for the 4MB allocations. > Currently lustre uses a 4 page water mark to determine if we allocate using vmalloc. Even > using kmalloc for 4 pages has shown high failure rates on some systems. It gets even more > messy with 64K page systems like ppc64 boxes. Now I'm not suggesting to port the larger > allocations to vmalloc either since issues have been founded with using vmalloc. For example > when using large stripe count files the MDS rpc generated crosses the 4 page line and vmalloc > is used. Using vmalloc caused a global spinlock to be taken which causes meta data operations > to serialized on the MDS servers. It's not the LARGE functions that do the switching? For example OBD_ALLOC ends up at __OBD_MALLOC_VERBOSE, which as far as I can see calls kmalloc (with __GFP_ZERO, and hance the use of kzalloc). julia -- 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/