From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1751839AbbEAUrk (ORCPT ); Fri, 1 May 2015 16:47:40 -0400 Received: from mail.linuxfoundation.org ([140.211.169.12]:33798 "EHLO mail.linuxfoundation.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1750844AbbEAUri (ORCPT ); Fri, 1 May 2015 16:47:38 -0400 Date: Fri, 1 May 2015 22:47:29 +0200 From: Greg Kroah-Hartman To: "Simmons, James A." Cc: "'Julia Lawall'" , "devel@driverdev.osuosl.org" , "kernel-janitors@vger.kernel.org" , "linux-kernel@vger.kernel.org" , Oleg Drokin , "HPDD-discuss@lists.01.org" Subject: Re: [HPDD-discuss] [PATCH 2/11] Staging: lustre: fld: Use kzalloc and kfree Message-ID: <20150501204729.GA2265@kroah.com> References: <1430495482-933-1-git-send-email-Julia.Lawall@lip6.fr> <1430495482-933-11-git-send-email-Julia.Lawall@lip6.fr> <524505df3433441494cf082a425f2ee7@EXCHCS32.ornl.gov> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <524505df3433441494cf082a425f2ee7@EXCHCS32.ornl.gov> User-Agent: Mutt/1.5.23 (2014-03-12) Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Fri, May 01, 2015 at 08:18:56PM +0000, 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). > > Yes the LARGE functions do the switching. I was expecting also patches to remove the > OBD_ALLOC_LARGE functions as well which is not the case here. I do have one question still. The > macro __OBD_MALLOC_VERBOSE allowed the ability to simulate memory allocation failures at > a certain percentage rate. Does something exist in the kernel to duplicate that functionality? Yes, no need for lustre to duplicate yet-another-thing the kernel already provides :)