From: Christoph Hellwig <hch@infradead.org>
To: Matthew Wilcox <willy@infradead.org>
Cc: Christoph Hellwig <hch@infradead.org>,
Robin Murphy <robin.murphy@arm.com>,
Michal Hocko <mhocko@suse.com>, Will Deacon <will.deacon@arm.com>,
Levin Alexander <Alexander.Levin@microsoft.com>,
linux-mm@kvack.org, Christopher Lameter <cl@linux.com>,
Nicolas Boichat <drinkcat@chromium.org>,
Huaisheng Ye <yehs1@lenovo.com>,
David Rientjes <rientjes@google.com>,
yingjoe.chen@mediatek.com, Vlastimil Babka <vbabka@suse.cz>,
Tomasz Figa <tfiga@google.com>,
Mike Rapoport <rppt@linux.vnet.ibm.com>,
Matthias Brugger <matthias.bgg@gmail.com>,
Joonsoo Kim <iamjoonsoo.kim@lge.com>,
linux-arm-kernel@lists.infradead.org,
linux-kernel@vger.kernel.org, Pekka Enberg <penberg@kernel.org>,
iommu@lists.linux-foundation.org,
Andrew Morton <akpm@linux-foundation.org>,
Mel Gorman <mgorman@techsingularity.net>
Subject: Re: [PATCH v2 0/3] iommu/io-pgtable-arm-v7s: Use DMA32 zone for page tables
Date: Thu, 22 Nov 2018 07:19:41 -0800 [thread overview]
Message-ID: <20181122151941.GA2681@infradead.org> (raw)
In-Reply-To: <20181122151632.GP3065@bombadil.infradead.org>
On Thu, Nov 22, 2018 at 07:16:32AM -0800, Matthew Wilcox wrote:
> Yes, your allocations from the page_frag allocator have to have similar
> lifetimes. I thought that would be ideal for XFS though; as I understood
> the problem, these were per-IO allocations, and IOs to the same filesystem
> tend to take roughly the same amount of time. Sure, in an error case,
> some IOs will take a long time before timing out, but it should be OK
> to have pages unavailable during that time in these rare situations.
> What am I missing?
No, thee are allocations for meatada buffers, which can stay around
for a long time. Worse still that depends on usage, so one buffer
allocated from ma page might basically stay around forever, while
another one might get reclaimed very quickly.
WARNING: multiple messages have this Message-ID (diff)
From: Christoph Hellwig <hch-wEGCiKHe2LqWVfeAwA7xHQ@public.gmane.org>
To: Matthew Wilcox <willy-wEGCiKHe2LqWVfeAwA7xHQ@public.gmane.org>
Cc: Michal Hocko <mhocko-IBi9RG/b67k@public.gmane.org>,
Will Deacon <will.deacon-5wv7dgnIgG8@public.gmane.org>,
Levin Alexander
<Alexander.Levin-0li6OtcxBFHby3iVrkZq2A@public.gmane.org>,
linux-mm-Bw31MaZKKs3YtjvyW6yDsg@public.gmane.org,
Christopher Lameter <cl-vYTEC60ixJUAvxtiuMwx3w@public.gmane.org>,
Nicolas Boichat
<drinkcat-F7+t8E8rja9g9hUCZPvPmw@public.gmane.org>,
Huaisheng Ye <yehs1-6jq1YtArVR3QT0dZR+AlfA@public.gmane.org>,
Vlastimil Babka <vbabka-AlSwsSmVLrQ@public.gmane.org>,
David Rientjes <rientjes-hpIqsD4AKlfQT0dZR+AlfA@public.gmane.org>,
yingjoe.chen-NuS5LvNUpcJWk0Htik3J/w@public.gmane.org,
Tomasz Figa <tfiga-hpIqsD4AKlfQT0dZR+AlfA@public.gmane.org>,
Mike Rapoport
<rppt-23VcF4HTsmIX0ybBhKVfKdBPR1lH4CV8@public.gmane.org>,
Matthias Brugger
<matthias.bgg-Re5JQEeQqe8AvxtiuMwx3w@public.gmane.org>,
Joonsoo Kim <iamjoonsoo.kim-Hm3cg6mZ9cc@public.gmane.org>,
linux-arm-kernel-IAPFreCvJWM7uuMidbF8XUB+6BGkLq7r@public.gmane.org,
Robin Murphy <robin.murphy-5wv7dgnIgG8@public.gmane.org>,
linux-kernel-u79uwXL29TY76Z2rM5mHXA@public.gmane.org,
Pekka Enberg <penberg-DgEjT+Ai2ygdnm+yROfE0A@public.gmane.org>,
iommu-cunTk1MwBs9QetFLy7KEm3xJsTq8ys+cHZ5vskTnxNA@public.gmane.org,
Andrew Morton
<akpm-de/tnXTf+JLsfHDXvbKv3WD2FQJk+8+b@public.gmane.org>,
Mel Gorman
<mgorman-3eNAlZScCAx27rWaFMvyedHuzzzSOjJt@public.gmane.org>
Subject: Re: [PATCH v2 0/3] iommu/io-pgtable-arm-v7s: Use DMA32 zone for page tables
Date: Thu, 22 Nov 2018 07:19:41 -0800 [thread overview]
Message-ID: <20181122151941.GA2681@infradead.org> (raw)
In-Reply-To: <20181122151632.GP3065-PfSpb0PWhxZc2C7mugBRk2EX/6BAtgUQ@public.gmane.org>
On Thu, Nov 22, 2018 at 07:16:32AM -0800, Matthew Wilcox wrote:
> Yes, your allocations from the page_frag allocator have to have similar
> lifetimes. I thought that would be ideal for XFS though; as I understood
> the problem, these were per-IO allocations, and IOs to the same filesystem
> tend to take roughly the same amount of time. Sure, in an error case,
> some IOs will take a long time before timing out, but it should be OK
> to have pages unavailable during that time in these rare situations.
> What am I missing?
No, thee are allocations for meatada buffers, which can stay around
for a long time. Worse still that depends on usage, so one buffer
allocated from ma page might basically stay around forever, while
another one might get reclaimed very quickly.
WARNING: multiple messages have this Message-ID (diff)
From: hch@infradead.org (Christoph Hellwig)
To: linux-arm-kernel@lists.infradead.org
Subject: [PATCH v2 0/3] iommu/io-pgtable-arm-v7s: Use DMA32 zone for page tables
Date: Thu, 22 Nov 2018 07:19:41 -0800 [thread overview]
Message-ID: <20181122151941.GA2681@infradead.org> (raw)
In-Reply-To: <20181122151632.GP3065@bombadil.infradead.org>
On Thu, Nov 22, 2018 at 07:16:32AM -0800, Matthew Wilcox wrote:
> Yes, your allocations from the page_frag allocator have to have similar
> lifetimes. I thought that would be ideal for XFS though; as I understood
> the problem, these were per-IO allocations, and IOs to the same filesystem
> tend to take roughly the same amount of time. Sure, in an error case,
> some IOs will take a long time before timing out, but it should be OK
> to have pages unavailable during that time in these rare situations.
> What am I missing?
No, thee are allocations for meatada buffers, which can stay around
for a long time. Worse still that depends on usage, so one buffer
allocated from ma page might basically stay around forever, while
another one might get reclaimed very quickly.
next prev parent reply other threads:[~2018-11-22 15:19 UTC|newest]
Thread overview: 96+ messages / expand[flat|nested] mbox.gz Atom feed top
2018-11-11 9:03 [PATCH v2 0/3] iommu/io-pgtable-arm-v7s: Use DMA32 zone for page tables Nicolas Boichat
2018-11-11 9:03 ` Nicolas Boichat
2018-11-11 9:03 ` Nicolas Boichat
2018-11-11 9:03 ` [PATCH v2 1/3] mm: slab/slub: Add check_slab_flags function to check for valid flags Nicolas Boichat
2018-11-11 9:03 ` Nicolas Boichat
2018-11-11 9:03 ` Nicolas Boichat
2018-11-11 9:03 ` [PATCH v2 2/3] mm: Add support for SLAB_CACHE_DMA32 Nicolas Boichat
2018-11-11 9:03 ` Nicolas Boichat
2018-11-11 9:03 ` Nicolas Boichat
2018-11-21 18:32 ` Christopher Lameter
2018-11-21 18:32 ` Christopher Lameter
2018-11-22 0:52 ` Nicolas Boichat
2018-11-22 0:52 ` Nicolas Boichat
2018-11-22 0:52 ` Nicolas Boichat
2018-11-11 9:03 ` [PATCH v2 3/3] iommu/io-pgtable-arm-v7s: Request DMA32 memory, and improve debugging Nicolas Boichat
2018-11-11 9:03 ` Nicolas Boichat
2018-11-11 9:03 ` Nicolas Boichat
2018-11-21 16:46 ` Will Deacon
2018-11-21 16:46 ` Will Deacon
2018-11-21 17:38 ` Christopher Lameter
2018-11-21 17:38 ` Christopher Lameter
2018-11-21 17:43 ` Robin Murphy
2018-11-21 17:43 ` Robin Murphy
2018-11-21 18:18 ` Christopher Lameter
2018-11-21 18:18 ` Christopher Lameter
2018-11-21 18:02 ` Michal Hocko
2018-11-21 18:02 ` Michal Hocko
2018-11-22 1:20 ` Nicolas Boichat
2018-11-22 1:20 ` Nicolas Boichat
2018-11-22 1:20 ` Nicolas Boichat
2018-11-23 12:15 ` Vlastimil Babka
2018-11-23 12:15 ` Vlastimil Babka
2018-11-21 18:20 ` [PATCH v2 0/3] iommu/io-pgtable-arm-v7s: Use DMA32 zone for page tables Christopher Lameter
2018-11-21 18:20 ` Christopher Lameter
2018-11-21 21:38 ` Matthew Wilcox
2018-11-21 21:38 ` Matthew Wilcox
2018-11-21 21:38 ` Matthew Wilcox
2018-11-21 22:26 ` Robin Murphy
2018-11-21 22:26 ` Robin Murphy
2018-11-21 22:26 ` Robin Murphy
2018-11-22 1:05 ` Nicolas Boichat
2018-11-22 1:05 ` Nicolas Boichat
2018-11-22 1:05 ` Nicolas Boichat
2018-11-22 2:35 ` Matthew Wilcox
2018-11-22 2:35 ` Matthew Wilcox
2018-11-22 2:35 ` Matthew Wilcox
2018-11-22 5:56 ` Nicolas Boichat
2018-11-22 5:56 ` Nicolas Boichat
2018-11-22 5:56 ` Nicolas Boichat
2018-11-22 8:26 ` Christoph Hellwig
2018-11-22 8:26 ` Christoph Hellwig
2018-11-22 8:26 ` Christoph Hellwig
2018-11-22 15:16 ` Matthew Wilcox
2018-11-22 15:16 ` Matthew Wilcox
2018-11-22 15:16 ` Matthew Wilcox
2018-11-22 15:19 ` Christoph Hellwig [this message]
2018-11-22 15:19 ` Christoph Hellwig
2018-11-22 15:19 ` Christoph Hellwig
2018-11-22 8:23 ` Christoph Hellwig
2018-11-22 8:23 ` Christoph Hellwig
2018-11-22 8:23 ` Christoph Hellwig
2018-11-23 3:04 ` Nicolas Boichat
2018-11-23 3:04 ` Nicolas Boichat
2018-11-23 3:04 ` Nicolas Boichat
2018-11-23 5:37 ` Nicolas Boichat
2018-11-23 5:37 ` Nicolas Boichat
2018-11-23 5:37 ` Nicolas Boichat
2018-11-23 12:23 ` Vlastimil Babka
2018-11-23 12:23 ` Vlastimil Babka
2018-11-23 12:23 ` Vlastimil Babka
2018-11-23 12:30 ` Michal Hocko
2018-11-23 12:30 ` Michal Hocko
2018-11-23 12:30 ` Michal Hocko
2018-11-26 8:02 ` Christoph Hellwig
2018-11-26 8:02 ` Christoph Hellwig
2018-11-26 8:02 ` Christoph Hellwig
2018-11-28 8:55 ` Nicolas Boichat
2018-11-28 8:55 ` Nicolas Boichat
2018-11-28 8:55 ` Nicolas Boichat
2018-12-04 9:37 ` Nicolas Boichat
2018-12-04 9:37 ` Nicolas Boichat
2018-12-04 14:35 ` Vlastimil Babka
2018-12-04 14:35 ` Vlastimil Babka
2018-12-04 14:35 ` Vlastimil Babka
2018-12-05 2:04 ` Nicolas Boichat
2018-12-05 2:04 ` Nicolas Boichat
2018-12-05 2:04 ` Nicolas Boichat
2018-12-05 5:51 ` Nicolas Boichat
2018-12-05 5:51 ` Nicolas Boichat
2018-12-05 5:51 ` Nicolas Boichat
2018-12-05 14:41 ` Will Deacon
2018-12-05 14:41 ` Will Deacon
2018-12-05 14:41 ` Will Deacon
2018-12-04 16:28 ` Will Deacon
2018-12-04 16:28 ` Will Deacon
2018-12-04 16:28 ` Will Deacon
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