From: Alexander Duyck <alexander.h.duyck@linux.intel.com>
To: David Hildenbrand <david@redhat.com>,
Alexander Duyck <alexander.duyck@gmail.com>,
virtio-dev@lists.oasis-open.org, kvm@vger.kernel.org,
mst@redhat.com, catalin.marinas@arm.com, dave.hansen@intel.com,
linux-kernel@vger.kernel.org, willy@infradead.org,
mhocko@kernel.org, linux-mm@kvack.org, akpm@linux-foundation.org,
will@kernel.org, linux-arm-kernel@lists.infradead.org,
osalvador@suse.de
Cc: yang.zhang.wz@gmail.com, pagupta@redhat.com,
konrad.wilk@oracle.com, nitesh@redhat.com, riel@surriel.com,
lcapitulino@redhat.com, wei.w.wang@intel.com,
aarcange@redhat.com, ying.huang@intel.com, pbonzini@redhat.com,
dan.j.williams@intel.com, fengguang.wu@intel.com,
kirill.shutemov@linux.intel.com
Subject: Re: [PATCH v9 1/8] mm: Add per-cpu logic to page shuffling
Date: Tue, 10 Sep 2019 15:11:50 -0700 [thread overview]
Message-ID: <3de2409415b20440d5c8f3016ed78fde3d106dc8.camel@linux.intel.com> (raw)
In-Reply-To: <0df2e5d0-af92-04b4-aa7d-891387874039@redhat.com>
On Mon, 2019-09-09 at 10:14 +0200, David Hildenbrand wrote:
> On 07.09.19 19:25, Alexander Duyck wrote:
> > From: Alexander Duyck <alexander.h.duyck@linux.intel.com>
> >
> > Change the logic used to generate randomness in the suffle path so that we
> > can avoid cache line bouncing. The previous logic was sharing the offset
> > and entropy word between all CPUs. As such this can result in cache line
> > bouncing and will ultimately hurt performance when enabled.
>
> So, usually we perform such changes if there is real evidence. Do you
> have any such performance numbers to back your claims?
I don't have any numbers. From what I can tell the impact is small enough
that this doesn't really have much impact.
With that being the case I can probably just drop this patch. I will
instead just use "rand & 1" in the 2nd patch to generate the return value
which was what was previously done in add_to_free_area_random.
WARNING: multiple messages have this Message-ID (diff)
From: Alexander Duyck <alexander.h.duyck@linux.intel.com>
To: David Hildenbrand <david@redhat.com>,
Alexander Duyck <alexander.duyck@gmail.com>,
virtio-dev@lists.oasis-open.org, kvm@vger.kernel.org,
mst@redhat.com, catalin.marinas@arm.com, dave.hansen@intel.com,
linux-kernel@vger.kernel.org, willy@infradead.org,
mhocko@kernel.org, linux-mm@kvack.org,
akpm@linux-foundation.org, will@kernel.org,
linux-arm-kernel@lists.infradead.org, osalvador@suse.de
Cc: yang.zhang.wz@gmail.com, pagupta@redhat.com, riel@surriel.com,
konrad.wilk@oracle.com, ying.huang@intel.com,
lcapitulino@redhat.com, wei.w.wang@intel.com,
aarcange@redhat.com, nitesh@redhat.com, pbonzini@redhat.com,
dan.j.williams@intel.com, fengguang.wu@intel.com,
kirill.shutemov@linux.intel.com
Subject: Re: [PATCH v9 1/8] mm: Add per-cpu logic to page shuffling
Date: Tue, 10 Sep 2019 15:11:50 -0700 [thread overview]
Message-ID: <3de2409415b20440d5c8f3016ed78fde3d106dc8.camel@linux.intel.com> (raw)
In-Reply-To: <0df2e5d0-af92-04b4-aa7d-891387874039@redhat.com>
On Mon, 2019-09-09 at 10:14 +0200, David Hildenbrand wrote:
> On 07.09.19 19:25, Alexander Duyck wrote:
> > From: Alexander Duyck <alexander.h.duyck@linux.intel.com>
> >
> > Change the logic used to generate randomness in the suffle path so that we
> > can avoid cache line bouncing. The previous logic was sharing the offset
> > and entropy word between all CPUs. As such this can result in cache line
> > bouncing and will ultimately hurt performance when enabled.
>
> So, usually we perform such changes if there is real evidence. Do you
> have any such performance numbers to back your claims?
I don't have any numbers. From what I can tell the impact is small enough
that this doesn't really have much impact.
With that being the case I can probably just drop this patch. I will
instead just use "rand & 1" in the 2nd patch to generate the return value
which was what was previously done in add_to_free_area_random.
_______________________________________________
linux-arm-kernel mailing list
linux-arm-kernel@lists.infradead.org
http://lists.infradead.org/mailman/listinfo/linux-arm-kernel
WARNING: multiple messages have this Message-ID (diff)
From: Alexander Duyck <alexander.h.duyck@linux.intel.com>
To: David Hildenbrand <david@redhat.com>,
Alexander Duyck <alexander.duyck@gmail.com>,
virtio-dev@lists.oasis-open.org, kvm@vger.kernel.org,
mst@redhat.com, catalin.marinas@arm.com, dave.hansen@intel.com,
linux-kernel@vger.kernel.org, willy@infradead.org,
mhocko@kernel.org, linux-mm@kvack.org, akpm@linux-foundation.org,
will@kernel.org, linux-arm-kernel@lists.infradead.org,
osalvador@suse.de
Cc: yang.zhang.wz@gmail.com, pagupta@redhat.com,
konrad.wilk@oracle.com, nitesh@redhat.com, riel@surriel.com,
lcapitulino@redhat.com, wei.w.wang@intel.com,
aarcange@redhat.com, ying.huang@intel.com, pbonzini@redhat.com,
dan.j.williams@intel.com, fengguang.wu@intel.com,
kirill.shutemov@linux.intel.com
Subject: [virtio-dev] Re: [PATCH v9 1/8] mm: Add per-cpu logic to page shuffling
Date: Tue, 10 Sep 2019 15:11:50 -0700 [thread overview]
Message-ID: <3de2409415b20440d5c8f3016ed78fde3d106dc8.camel@linux.intel.com> (raw)
In-Reply-To: <0df2e5d0-af92-04b4-aa7d-891387874039@redhat.com>
On Mon, 2019-09-09 at 10:14 +0200, David Hildenbrand wrote:
> On 07.09.19 19:25, Alexander Duyck wrote:
> > From: Alexander Duyck <alexander.h.duyck@linux.intel.com>
> >
> > Change the logic used to generate randomness in the suffle path so that we
> > can avoid cache line bouncing. The previous logic was sharing the offset
> > and entropy word between all CPUs. As such this can result in cache line
> > bouncing and will ultimately hurt performance when enabled.
>
> So, usually we perform such changes if there is real evidence. Do you
> have any such performance numbers to back your claims?
I don't have any numbers. From what I can tell the impact is small enough
that this doesn't really have much impact.
With that being the case I can probably just drop this patch. I will
instead just use "rand & 1" in the 2nd patch to generate the return value
which was what was previously done in add_to_free_area_random.
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next prev parent reply other threads:[~2019-09-10 22:11 UTC|newest]
Thread overview: 241+ messages / expand[flat|nested] mbox.gz Atom feed top
2019-09-07 17:25 [PATCH v9 0/8] stg mail -e --version=v9 \ Alexander Duyck
2019-09-07 17:25 ` [virtio-dev] " Alexander Duyck
2019-09-07 17:25 ` Alexander Duyck
2019-09-07 17:25 ` [PATCH v9 1/8] mm: Add per-cpu logic to page shuffling Alexander Duyck
2019-09-07 17:25 ` [virtio-dev] " Alexander Duyck
2019-09-07 17:25 ` Alexander Duyck
2019-09-09 8:14 ` David Hildenbrand
2019-09-09 8:14 ` [virtio-dev] " David Hildenbrand
2019-09-09 8:14 ` David Hildenbrand
2019-09-09 15:11 ` Alexander Duyck
2019-09-09 15:11 ` [virtio-dev] " Alexander Duyck
2019-09-09 15:11 ` Alexander Duyck
2019-09-09 15:11 ` Alexander Duyck
2019-09-10 12:11 ` Michal Hocko
2019-09-10 12:11 ` Michal Hocko
2019-09-10 22:14 ` Alexander Duyck
2019-09-10 22:14 ` [virtio-dev] " Alexander Duyck
2019-09-10 22:14 ` Alexander Duyck
2019-09-10 22:14 ` Alexander Duyck
2019-09-10 22:11 ` Alexander Duyck [this message]
2019-09-10 22:11 ` [virtio-dev] " Alexander Duyck
2019-09-10 22:11 ` Alexander Duyck
2019-09-10 22:11 ` Alexander Duyck
2019-09-09 9:07 ` Kirill A. Shutemov
2019-09-09 9:07 ` Kirill A. Shutemov
2019-09-09 15:12 ` Alexander Duyck
2019-09-09 15:12 ` [virtio-dev] " Alexander Duyck
2019-09-09 15:12 ` Alexander Duyck
2019-09-09 15:12 ` Alexander Duyck
2019-09-07 17:25 ` [PATCH v9 2/8] mm: Adjust shuffle code to allow for future coalescing Alexander Duyck
2019-09-07 17:25 ` [virtio-dev] " Alexander Duyck
2019-09-07 17:25 ` Alexander Duyck
2019-09-09 8:19 ` David Hildenbrand
2019-09-09 8:19 ` [virtio-dev] " David Hildenbrand
2019-09-09 8:19 ` David Hildenbrand
2019-09-09 9:47 ` Kirill A. Shutemov
2019-09-09 9:47 ` Kirill A. Shutemov
2019-09-09 15:22 ` Alexander Duyck
2019-09-09 15:22 ` [virtio-dev] " Alexander Duyck
2019-09-09 15:22 ` Alexander Duyck
2019-09-09 15:22 ` Alexander Duyck
2019-09-09 15:35 ` Kirill A. Shutemov
2019-09-09 15:35 ` Kirill A. Shutemov
2019-09-09 15:37 ` Alexander Duyck
2019-09-09 15:37 ` [virtio-dev] " Alexander Duyck
2019-09-09 15:37 ` Alexander Duyck
2019-09-09 15:37 ` Alexander Duyck
2019-09-09 16:43 ` Alexander Duyck
2019-09-09 16:43 ` [virtio-dev] " Alexander Duyck
2019-09-09 16:43 ` Alexander Duyck
2019-09-09 16:43 ` Alexander Duyck
2019-09-09 17:00 ` Kirill A. Shutemov
2019-09-09 17:00 ` Kirill A. Shutemov
2019-09-10 12:20 ` Michal Hocko
2019-09-10 12:20 ` Michal Hocko
2019-09-10 14:48 ` Alexander Duyck
2019-09-10 14:48 ` [virtio-dev] " Alexander Duyck
2019-09-10 14:48 ` Alexander Duyck
2019-09-10 14:48 ` Alexander Duyck
2019-09-07 17:25 ` [PATCH v9 3/8] mm: Move set/get_pcppage_migratetype to mmzone.h Alexander Duyck
2019-09-07 17:25 ` [virtio-dev] " Alexander Duyck
2019-09-07 17:25 ` Alexander Duyck
2019-09-09 8:22 ` David Hildenbrand
2019-09-09 8:22 ` [virtio-dev] " David Hildenbrand
2019-09-09 8:22 ` David Hildenbrand
2019-09-09 9:56 ` Kirill A. Shutemov
2019-09-09 9:56 ` Kirill A. Shutemov
2019-09-09 18:01 ` Alexander Duyck
2019-09-09 18:01 ` [virtio-dev] " Alexander Duyck
2019-09-09 18:01 ` Alexander Duyck
2019-09-09 18:01 ` Alexander Duyck
2019-09-09 18:12 ` Alexander Duyck
2019-09-09 18:12 ` [virtio-dev] " Alexander Duyck
2019-09-09 18:12 ` Alexander Duyck
2019-09-09 18:12 ` Alexander Duyck
2019-09-10 12:23 ` Michal Hocko
2019-09-10 12:23 ` Michal Hocko
2019-09-10 14:46 ` Alexander Duyck
2019-09-10 14:46 ` [virtio-dev] " Alexander Duyck
2019-09-10 14:46 ` Alexander Duyck
2019-09-10 14:46 ` Alexander Duyck
2019-09-10 17:45 ` Michal Hocko
2019-09-10 17:45 ` Michal Hocko
2019-09-10 20:26 ` Alexander Duyck
2019-09-10 20:26 ` [virtio-dev] " Alexander Duyck
2019-09-10 20:26 ` Alexander Duyck
2019-09-10 20:26 ` Alexander Duyck
2019-09-07 17:25 ` [PATCH v9 4/8] mm: Use zone and order instead of free area in free_list manipulators Alexander Duyck
2019-09-07 17:25 ` [virtio-dev] " Alexander Duyck
2019-09-07 17:25 ` Alexander Duyck
2019-09-10 12:27 ` Michal Hocko
2019-09-10 12:27 ` Michal Hocko
2019-09-07 17:25 ` [PATCH v9 5/8] arm64: Move hugetlb related definitions out of pgtable.h to page-defs.h Alexander Duyck
2019-09-07 17:25 ` [virtio-dev] " Alexander Duyck
2019-09-07 17:25 ` Alexander Duyck
2019-09-09 8:52 ` David Hildenbrand
2019-09-09 8:52 ` [virtio-dev] " David Hildenbrand
2019-09-09 8:52 ` David Hildenbrand
2019-09-09 15:27 ` Alexander Duyck
2019-09-09 15:27 ` [virtio-dev] " Alexander Duyck
2019-09-09 15:27 ` Alexander Duyck
2019-09-09 15:27 ` Alexander Duyck
2019-09-17 17:48 ` Will Deacon
2019-09-17 17:48 ` Will Deacon
2019-09-17 20:07 ` Alexander Duyck
2019-09-17 20:07 ` [virtio-dev] " Alexander Duyck
2019-09-17 20:07 ` Alexander Duyck
2019-09-17 20:07 ` Alexander Duyck
2019-09-07 17:25 ` [PATCH v9 6/8] mm: Introduce Reported pages Alexander Duyck
2019-09-07 17:25 ` [virtio-dev] " Alexander Duyck
2019-09-07 17:25 ` Alexander Duyck
2019-09-09 14:42 ` Kirill A. Shutemov
2019-09-09 14:42 ` Kirill A. Shutemov
2019-09-09 16:25 ` Alexander Duyck
2019-09-09 16:25 ` [virtio-dev] " Alexander Duyck
2019-09-09 16:25 ` Alexander Duyck
2019-09-09 16:25 ` Alexander Duyck
2019-09-09 16:33 ` Kirill A. Shutemov
2019-09-09 16:33 ` Kirill A. Shutemov
2019-09-07 17:26 ` [PATCH v9 7/8] virtio-balloon: Pull page poisoning config out of free page hinting Alexander Duyck
2019-09-07 17:26 ` [virtio-dev] " Alexander Duyck
2019-09-07 17:26 ` Alexander Duyck
2019-09-09 8:59 ` David Hildenbrand
2019-09-09 8:59 ` [virtio-dev] " David Hildenbrand
2019-09-09 8:59 ` David Hildenbrand
2019-09-09 15:31 ` Alexander Duyck
2019-09-09 15:31 ` [virtio-dev] " Alexander Duyck
2019-09-09 15:31 ` Alexander Duyck
2019-09-09 15:31 ` Alexander Duyck
2019-09-07 17:26 ` [PATCH v9 8/8] virtio-balloon: Add support for providing unused page reports to host Alexander Duyck
2019-09-07 17:26 ` [virtio-dev] " Alexander Duyck
2019-09-07 17:26 ` Alexander Duyck
2019-09-07 17:34 ` [PATCH v9 0/8] mm / virtio: Provide support for unused page reporting Alexander Duyck
2019-09-07 17:34 ` [virtio-dev] " Alexander Duyck
2019-09-07 17:34 ` Alexander Duyck
2019-09-07 17:34 ` Alexander Duyck
2019-09-10 12:42 ` [PATCH v9 0/8] stg mail -e --version=v9 \ Michal Hocko
2019-09-10 12:42 ` Michal Hocko
2019-09-10 14:42 ` Alexander Duyck
2019-09-10 14:42 ` [virtio-dev] " Alexander Duyck
2019-09-10 14:42 ` Alexander Duyck
2019-09-10 14:42 ` Alexander Duyck
2019-09-10 14:47 ` Michal Hocko
2019-09-10 14:47 ` Michal Hocko
2019-09-10 16:05 ` Alexander Duyck
2019-09-10 16:05 ` [virtio-dev] " Alexander Duyck
2019-09-10 16:05 ` Alexander Duyck
2019-09-10 16:05 ` Alexander Duyck
2019-09-10 16:18 ` [virtio-dev] " Dr. David Alan Gilbert
2019-09-10 16:18 ` Dr. David Alan Gilbert
2019-09-10 16:18 ` Dr. David Alan Gilbert
2019-09-10 16:22 ` David Hildenbrand
2019-09-10 16:22 ` David Hildenbrand
2019-09-10 16:22 ` David Hildenbrand
2019-09-11 9:23 ` Michael S. Tsirkin
2019-09-11 9:23 ` Michael S. Tsirkin
2019-09-11 9:23 ` Michael S. Tsirkin
2019-09-11 9:50 ` David Hildenbrand
2019-09-11 9:50 ` David Hildenbrand
2019-09-11 9:50 ` David Hildenbrand
2019-09-10 17:52 ` Michal Hocko
2019-09-10 17:52 ` Michal Hocko
2019-09-10 18:00 ` Michal Hocko
2019-09-10 18:00 ` Michal Hocko
2019-09-10 20:37 ` Alexander Duyck
2019-09-10 20:37 ` [virtio-dev] " Alexander Duyck
2019-09-10 20:37 ` Alexander Duyck
2019-09-10 20:37 ` Alexander Duyck
2019-09-10 21:23 ` Alexander Duyck
2019-09-10 21:23 ` [virtio-dev] " Alexander Duyck
2019-09-10 21:23 ` Alexander Duyck
2019-09-10 21:23 ` Alexander Duyck
2019-09-11 11:36 ` Michal Hocko
2019-09-11 11:36 ` Michal Hocko
2019-09-11 11:47 ` David Hildenbrand
2019-09-11 11:47 ` [virtio-dev] " David Hildenbrand
2019-09-11 11:47 ` David Hildenbrand
2019-09-11 12:08 ` Michael S. Tsirkin
2019-09-11 12:08 ` [virtio-dev] " Michael S. Tsirkin
2019-09-11 12:08 ` Michael S. Tsirkin
2019-09-11 12:19 ` Michal Hocko
2019-09-11 12:19 ` Michal Hocko
2019-09-11 12:25 ` Michal Hocko
2019-09-11 12:25 ` Michal Hocko
2019-09-11 12:42 ` David Hildenbrand
2019-09-11 12:42 ` [virtio-dev] " David Hildenbrand
2019-09-11 12:42 ` David Hildenbrand
2019-09-11 12:54 ` Michal Hocko
2019-09-11 12:54 ` Michal Hocko
2019-09-11 13:03 ` David Hildenbrand
2019-09-11 13:03 ` [virtio-dev] " David Hildenbrand
2019-09-11 13:03 ` David Hildenbrand
2019-09-11 13:20 ` Michal Hocko
2019-09-11 13:20 ` Michal Hocko
2019-09-11 13:51 ` Michal Hocko
2019-09-11 13:51 ` Michal Hocko
2019-09-11 16:09 ` David Hildenbrand
2019-09-11 16:09 ` [virtio-dev] " David Hildenbrand
2019-09-11 16:09 ` David Hildenbrand
2019-09-12 7:16 ` Michal Hocko
2019-09-12 7:16 ` Michal Hocko
2019-09-12 7:47 ` David Hildenbrand
2019-09-12 7:47 ` [virtio-dev] " David Hildenbrand
2019-09-12 7:47 ` David Hildenbrand
2019-09-12 9:26 ` Michal Hocko
2019-09-12 9:26 ` Michal Hocko
2019-09-12 12:00 ` Nitesh Narayan Lal
2019-09-12 12:00 ` [virtio-dev] " Nitesh Narayan Lal
2019-09-12 12:00 ` Nitesh Narayan Lal
2019-09-11 14:03 ` Nitesh Narayan Lal
2019-09-11 14:03 ` [virtio-dev] " Nitesh Narayan Lal
2019-09-11 14:03 ` Nitesh Narayan Lal
2019-09-11 16:02 ` David Hildenbrand
2019-09-11 16:02 ` [virtio-dev] " David Hildenbrand
2019-09-11 16:02 ` David Hildenbrand
2019-09-11 13:19 ` Nitesh Narayan Lal
2019-09-11 13:19 ` [virtio-dev] " Nitesh Narayan Lal
2019-09-11 13:19 ` Nitesh Narayan Lal
2019-09-11 12:55 ` Nitesh Narayan Lal
2019-09-11 12:55 ` [virtio-dev] " Nitesh Narayan Lal
2019-09-11 12:55 ` Nitesh Narayan Lal
2019-09-11 15:12 ` Alexander Duyck
2019-09-11 15:12 ` [virtio-dev] " Alexander Duyck
2019-09-11 15:12 ` Alexander Duyck
2019-09-11 15:12 ` Alexander Duyck
2019-09-12 9:19 ` Michal Hocko
2019-09-12 9:19 ` Michal Hocko
2019-09-12 10:24 ` Kirill A. Shutemov
2019-09-12 10:24 ` Kirill A. Shutemov
2019-09-12 11:11 ` Michal Hocko
2019-09-12 11:11 ` Michal Hocko
2019-09-12 15:42 ` Alexander Duyck
2019-09-12 15:42 ` [virtio-dev] " Alexander Duyck
2019-09-12 15:42 ` Alexander Duyck
2019-09-12 15:42 ` Alexander Duyck
2019-09-12 16:35 ` Mel Gorman
2019-09-12 16:35 ` Mel Gorman
2019-09-12 17:48 ` Alexander Duyck
2019-09-12 17:48 ` [virtio-dev] " Alexander Duyck
2019-09-12 17:48 ` Alexander Duyck
2019-09-12 17:48 ` Alexander Duyck
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