From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mail-la0-f54.google.com (mail-la0-f54.google.com [209.85.215.54]) by kanga.kvack.org (Postfix) with ESMTP id 078236B0036 for ; Fri, 23 May 2014 11:26:56 -0400 (EDT) Received: by mail-la0-f54.google.com with SMTP id pv20so4420704lab.13 for ; Fri, 23 May 2014 08:26:56 -0700 (PDT) Received: from mx2.parallels.com (mx2.parallels.com. [199.115.105.18]) by mx.google.com with ESMTPS id no1si6501354lbb.27.2014.05.23.08.26.54 for (version=TLSv1.2 cipher=ECDHE-RSA-AES128-GCM-SHA256 bits=128/128); Fri, 23 May 2014 08:26:55 -0700 (PDT) Date: Fri, 23 May 2014 19:26:43 +0400 From: Vladimir Davydov Subject: Re: [PATCH RFC 3/3] slub: reparent memcg caches' slabs on memcg offline Message-ID: <20140523152642.GD3147@esperanza> References: <20140516132234.GF32113@esperanza> <20140519152437.GB25889@esperanza> <537A4D27.1050909@parallels.com> <20140521150408.GB23193@esperanza> <20140522134726.GA3147@esperanza> MIME-Version: 1.0 Content-Type: text/plain; charset="us-ascii" Content-Disposition: inline In-Reply-To: Sender: owner-linux-mm@kvack.org List-ID: To: Christoph Lameter Cc: hannes@cmpxchg.org, mhocko@suse.cz, akpm@linux-foundation.org, linux-kernel@vger.kernel.org, linux-mm@kvack.org On Thu, May 22, 2014 at 02:25:30PM -0500, Christoph Lameter wrote: > slab_free calls __slab_free which can release slabs via > put_cpu_partial()/unfreeze_partials()/discard_slab() to the page > allocator. I'd rather have preemption enabled there. Hmm, why? IMO, calling __free_pages with preempt disabled won't hurt latency, because it proceeds really fast. BTW, we already call it for a bunch of pages from __slab_free() -> put_cpu_partial() -> unfreeze_partials() with irqs disabled, which is harder. FWIW, SLAB has the whole obj free path executed under local_irq_save/restore, and it doesn't bother enabling irqs for freeing pages. IMO, the latency improvement we can achieve by enabling preemption while calling __free_pages is rather minor, and it isn't worth complicating the code. Thanks. -- 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