From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from psmtp.com (na3sys010amx115.postini.com [74.125.245.115]) by kanga.kvack.org (Postfix) with SMTP id 77E926B0069 for ; Tue, 19 Jun 2012 19:21:04 -0400 (EDT) Date: Tue, 19 Jun 2012 18:21:02 -0500 From: Nathan Zimmer Subject: Re: [PATCH v2] tmpfs not interleaving properly Message-ID: <20120619232102.GA5698@gulag1.americas.sgi.com> References: <20120531143916.GA16162@gulag1.americas.sgi.com> <4FC7CFEB.5040009@gmail.com> <20120531132515.6af60152.akpm@linux-foundation.org> <4FC7D629.3090801@gmail.com> <20120601142437.GA13739@gulag1.americas.sgi.com> <4FC8FA47.70001@gmail.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <4FC8FA47.70001@gmail.com> Sender: owner-linux-mm@kvack.org List-ID: To: KOSAKI Motohiro Cc: Nathan Zimmer , Andrew Morton , hughd@google.com, npiggin@gmail.com, cl@linux.com, lee.schermerhorn@hp.com, linux-kernel@vger.kernel.org, linux-mm@kvack.org, stable@vger.kernel.org, riel@redhat.com On Fri, Jun 01, 2012 at 01:22:15PM -0400, KOSAKI Motohiro wrote: > (6/1/12 10:24 AM), Nathan Zimmer wrote: >> On Thu, May 31, 2012 at 04:35:53PM -0400, KOSAKI Motohiro wrote: >>> (5/31/12 4:25 PM), Andrew Morton wrote: >>>> On Thu, 31 May 2012 16:09:15 -0400 >>>> KOSAKI Motohiro wrote: >>>> >>>>>> --- a/mm/shmem.c >>>>>> +++ b/mm/shmem.c >>>>>> @@ -929,7 +929,7 @@ static struct page *shmem_alloc_page(gfp_t gfp, >>>>>> /* >>>>>> * alloc_page_vma() will drop the shared policy reference >>>>>> */ >>>>>> - return alloc_page_vma(gfp,&pvma, 0); >>>>>> + return alloc_page_vma(gfp,&pvma, info->node_offset<< PAGE_SHIFT ); >>>>> >>>>> 3rd argument of alloc_page_vma() is an address. This is type error. >>>> >>>> Well, it's an unsigned long... >>>> >>>> But yes, it is conceptually wrong and *looks* weird. I think we can >>>> address that by overcoming our peculair aversion to documenting our >>>> code, sigh. This? >>> >>> Sorry, no. >>> >>> addr agrument of alloc_pages_vma() have two meanings. >>> >>> 1) interleave node seed >>> 2) look-up key of shmem policy >>> >>> I think this patch break (2). shmem_get_policy(pol, addr) assume caller honor to >>> pass correct address. >> >> But the pseudo vma we generated in shmem_alloc_page the vm_ops are set to NULL. >> So get_vma_policy will return the policy provided by the pseudo vma and not reach >> the shmem_get_policy. > > yes, and it is bug source. we may need to change soon. I guess the right way is > to make vm_ops->interleave and interleave_nid uses it if povided. > If we provide vm_ops then won't shmem_get_policy get called? That would be an issue since shmem_get_policy assumes vm_file is non NULL. > btw, I don't think node_random() is good idea. it is random(pid + jiffies + cycle). > current->cpuset_mem_spread_rotor is per-thread value. but you now need per-inode > interleave offset. maybe, just inode addition is enough. Why do you need randomness? > I don't really need the randomness, the rotor should be good enough. The correct way to get that is cpuset_mem_spread_node(), yes? Also apologies for such a delay in my response. -- To unsubscribe, send a message with 'unsubscribe linux-mm' in the body to majordomo@kvack.org. For more info on Linux MM, see: http://www.linux-mm.org/ . Don't email: email@kvack.org