From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from psmtp.com (na3sys010amx139.postini.com [74.125.245.139]) by kanga.kvack.org (Postfix) with SMTP id 50C506B0033 for ; Wed, 19 Jun 2013 22:32:47 -0400 (EDT) Received: from /spool/local by e28smtp05.in.ibm.com with IBM ESMTP SMTP Gateway: Authorized Use Only! Violators will be prosecuted for from ; Thu, 20 Jun 2013 07:57:49 +0530 Received: from d28relay05.in.ibm.com (d28relay05.in.ibm.com [9.184.220.62]) by d28dlp02.in.ibm.com (Postfix) with ESMTP id 72A12394004F for ; Thu, 20 Jun 2013 08:02:40 +0530 (IST) Received: from d28av01.in.ibm.com (d28av01.in.ibm.com [9.184.220.63]) by d28relay05.in.ibm.com (8.13.8/8.13.8/NCO v10.0) with ESMTP id r5K2WZKr27721836 for ; Thu, 20 Jun 2013 08:02:36 +0530 Received: from d28av01.in.ibm.com (loopback [127.0.0.1]) by d28av01.in.ibm.com (8.14.4/8.13.1/NCO v10.0 AVout) with ESMTP id r5K2Wd87012369 for ; Thu, 20 Jun 2013 02:32:39 GMT Date: Thu, 20 Jun 2013 10:32:38 +0800 From: Wanpeng Li Subject: Re: [PATCH] slub: do not put a slab to cpu partial list when cpu_partial is 0 Message-ID: <20130620023238.GA27516@hacker.(null)> Reply-To: Wanpeng Li References: <1371623635-26575-1-git-send-email-iamjoonsoo.kim@lge.com> <51c1652d.246e320a.4057.ffffed4fSMTPIN_ADDED_BROKEN@mx.google.com> <20130619085250.GC12231@lge.com> <51c24c29.425c320a.433e.ffff9d8fSMTPIN_ADDED_BROKEN@mx.google.com> <20130620014439.GA13026@lge.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20130620014439.GA13026@lge.com> Sender: owner-linux-mm@kvack.org List-ID: To: Joonsoo Kim Cc: Pekka Enberg , Christoph Lameter , Matt Mackall , linux-mm@kvack.org, linux-kernel@vger.kernel.org On Thu, Jun 20, 2013 at 10:44:40AM +0900, Joonsoo Kim wrote: >On Thu, Jun 20, 2013 at 08:26:03AM +0800, Wanpeng Li wrote: >> On Wed, Jun 19, 2013 at 05:52:50PM +0900, Joonsoo Kim wrote: >> >On Wed, Jun 19, 2013 at 04:00:32PM +0800, Wanpeng Li wrote: >> >> On Wed, Jun 19, 2013 at 03:33:55PM +0900, Joonsoo Kim wrote: >> >> >In free path, we don't check number of cpu_partial, so one slab can >> >> >be linked in cpu partial list even if cpu_partial is 0. To prevent this, >> >> >we should check number of cpu_partial in put_cpu_partial(). >> >> > >> >> >> >> How about skip get_partial entirely? put_cpu_partial is called >> >> in two paths, one is during refill cpu partial lists in alloc >> >> slow path, the other is in free slow path. And cpu_partial is 0 >> >> just in debug mode. >> >> >> >> - alloc slow path, there is unnecessary to call get_partial >> >> since cpu partial lists won't be used in debug mode. >> >> - free slow patch, new.inuse won't be true in debug mode >> >> which lead to put_cpu_partial won't be called. >> >> >> > >> >In debug mode, put_cpu_partial() can't be called already on both path. >> >But, if we assign 0 to cpu_partial via sysfs, put_cpu_partial() will be called >> >on free slow path. On alloc slow path, it can't be called, because following >> >test in get_partial_node() is always failed. >> > >> >available > s->cpu_partial / 2 >> >> Is it always true? We can freeze slab from partial list, and >> s->cpu_partial is 0. > >Do you mean node partial list? > Yup. >At first, acquire_slab() is called for a cpu slab(not cpu partial list) >in get_partial_node(), and then, check above test. In this time, available >is always higher than 0, so, if we assign 0 to s->cpu_partial, we break >the loop and we don't try to get a slab for cpu partial list. > Agreed. Reviewed-by: Wanpeng Li >Thanks. > >> >> Regards, >> Wanpeng Li >> >> > >> >Thanks. >> > >> >> Regards, >> >> Wanpeng Li >> >> >> >> >Signed-off-by: Joonsoo Kim >> >> > >> >> >diff --git a/mm/slub.c b/mm/slub.c >> >> >index 57707f0..7033b4f 100644 >> >> >--- a/mm/slub.c >> >> >+++ b/mm/slub.c >> >> >@@ -1955,6 +1955,9 @@ static void put_cpu_partial(struct kmem_cache *s, struct page *page, int drain) >> >> > int pages; >> >> > int pobjects; >> >> > >> >> >+ if (!s->cpu_partial) >> >> >+ return; >> >> >+ >> >> > do { >> >> > pages = 0; >> >> > pobjects = 0; >> >> >-- >> >> >1.7.9.5 >> >> > >> >> >-- >> >> >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 >> >> >> >> -- >> >> 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 >> >> -- >> 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 -- 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