From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mail-wm0-f71.google.com (mail-wm0-f71.google.com [74.125.82.71]) by kanga.kvack.org (Postfix) with ESMTP id E63326B0038 for ; Sun, 26 Mar 2017 04:21:41 -0400 (EDT) Received: by mail-wm0-f71.google.com with SMTP id t189so14589634wmt.9 for ; Sun, 26 Mar 2017 01:21:41 -0700 (PDT) Received: from mail-wr0-x241.google.com (mail-wr0-x241.google.com. [2a00:1450:400c:c0c::241]) by mx.google.com with ESMTPS id p199si9846435wmd.130.2017.03.26.01.21.40 for (version=TLS1_2 cipher=ECDHE-RSA-AES128-GCM-SHA256 bits=128/128); Sun, 26 Mar 2017 01:21:40 -0700 (PDT) Received: by mail-wr0-x241.google.com with SMTP id w43so1220145wrb.1 for ; Sun, 26 Mar 2017 01:21:40 -0700 (PDT) Subject: Re: Page allocator order-0 optimizations merged References: <58b48b1f.F/jo2/WiSxvvGm/z%akpm@linux-foundation.org> <20170301144845.783f8cad@redhat.com> <83a0e3ef-acfa-a2af-2770-b9a92bda41bb@mellanox.com> <20170322234004.kffsce4owewgpqnm@techsingularity.net> <20170323144347.1e6f29de@redhat.com> <20170323145133.twzt4f5ci26vdyut@techsingularity.net> From: Tariq Toukan Message-ID: <779ab72d-94b9-1a28-c192-377e91383b4e@gmail.com> Date: Sun, 26 Mar 2017 11:21:37 +0300 MIME-Version: 1.0 In-Reply-To: <20170323145133.twzt4f5ci26vdyut@techsingularity.net> Content-Type: text/plain; charset=iso-8859-15; format=flowed Content-Transfer-Encoding: 7bit Sender: owner-linux-mm@kvack.org List-ID: To: Mel Gorman , Jesper Dangaard Brouer Cc: Tariq Toukan , "netdev@vger.kernel.org" , akpm@linux-foundation.org, linux-mm , Saeed Mahameed On 23/03/2017 4:51 PM, Mel Gorman wrote: > On Thu, Mar 23, 2017 at 02:43:47PM +0100, Jesper Dangaard Brouer wrote: >> On Wed, 22 Mar 2017 23:40:04 +0000 >> Mel Gorman wrote: >> >>> On Wed, Mar 22, 2017 at 07:39:17PM +0200, Tariq Toukan wrote: >>>>>>> This modification may slow allocations from IRQ context slightly >>>>>>> but the >>>>>>> main gain from the per-cpu allocator is that it scales better for >>>>>>> allocations from multiple contexts. There is an implicit >>>>>>> assumption that >>>>>>> intensive allocations from IRQ contexts on multiple CPUs from a single >>>>>>> NUMA node are rare >>>> Hi Mel, Jesper, and all. >>>> >>>> This assumption contradicts regular multi-stream traffic that is naturally >>>> handled >>>> over close numa cores. I compared iperf TCP multistream (8 streams) >>>> over CX4 (mlx5 driver) with kernels v4.10 (before this series) vs >>>> kernel v4.11-rc1 (with this series). >>>> I disabled the page-cache (recycle) mechanism to stress the page allocator, >>>> and see a drastic degradation in BW, from 47.5 G in v4.10 to 31.4 G in >>>> v4.11-rc1 (34% drop). >>>> I noticed queued_spin_lock_slowpath occupies 62.87% of CPU time. >>> >>> Can you get the stack trace for the spin lock slowpath to confirm it's >>> from IRQ context? >> >> AFAIK allocations happen in softirq. Argh and during review I missed >> that in_interrupt() also covers softirq. To Mel, can we use a in_irq() >> check instead? >> >> (p.s. just landed and got home) Glad to hear. Thanks for your suggestion. > > Not built or even boot tested. I'm unable to run tests at the moment Thanks Mel, I will test it soon. > > diff --git a/mm/page_alloc.c b/mm/page_alloc.c > index 6cbde310abed..f82225725bc1 100644 > --- a/mm/page_alloc.c > +++ b/mm/page_alloc.c > @@ -2481,7 +2481,7 @@ void free_hot_cold_page(struct page *page, bool cold) > unsigned long pfn = page_to_pfn(page); > int migratetype; > > - if (in_interrupt()) { > + if (in_irq()) { > __free_pages_ok(page, 0); > return; > } > @@ -2647,7 +2647,7 @@ static struct page *__rmqueue_pcplist(struct zone *zone, int migratetype, > { > struct page *page; > > - VM_BUG_ON(in_interrupt()); > + VM_BUG_ON(in_irq()); > > do { > if (list_empty(list)) { > @@ -2704,7 +2704,7 @@ struct page *rmqueue(struct zone *preferred_zone, > unsigned long flags; > struct page *page; > > - if (likely(order == 0) && !in_interrupt()) { > + if (likely(order == 0) && !in_irq()) { > page = rmqueue_pcplist(preferred_zone, zone, order, > gfp_flags, migratetype); > goto out; > -- 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