From: "Leizhen (ThunderTown)" <thunder.leizhen@huawei.com>
To: Jean-Philippe Brucker <jean-philippe.brucker@arm.com>,
"Jean-Philippe Brucker" <jean-philippe@linaro.org>,
John Garry <john.garry@huawei.com>,
"Robin Murphy" <robin.murphy@arm.com>,
Will Deacon <will@kernel.org>, Joerg Roedel <joro@8bytes.org>,
iommu <iommu@lists.linux-foundation.org>,
Omer Peleg <omer@cs.technion.ac.il>,
Adam Morrison <mad@cs.technion.ac.il>, Shaohua Li <shli@fb.com>,
Ben Serebrin <serebrin@google.com>,
David Woodhouse <David.Woodhouse@intel.com>,
linux-arm-kernel <linux-arm-kernel@lists.infradead.org>,
linux-kernel <linux-kernel@vger.kernel.org>
Subject: Re: [PATCH v2 0/2] iommu/iova: enhance the rcache optimization
Date: Fri, 23 Aug 2019 16:15:00 +0800 [thread overview]
Message-ID: <297e3718-eb31-d92a-1eb9-d4999fcd20c5@huawei.com> (raw)
In-Reply-To: <20190815121104.29140-1-thunder.leizhen@huawei.com>
Hi all,
Can anyone help review it?
On 2019/8/15 20:11, Zhen Lei wrote:
> v1 --> v2
> 1. I did not chagne the patches but added this cover-letter.
> 2. Add a batch of reviewers base on
> 9257b4a206fc ("iommu/iova: introduce per-cpu caching to iova allocation")
> 3. I described the problem I met in patch 2, but I hope below brief description
> can help people to quickly understand.
> Suppose there are six rcache sizes, each size can maximum hold 10000 IOVAs.
> --------------------------------------------
> | 4K | 8K | 16K | 32K | 64K | 128K |
> --------------------------------------------
> | 10000 | 9000 | 8500 | 8600 | 9200 | 7000 |
> --------------------------------------------
> As the above map displayed, the whole rcache buffered too many IOVAs. Now, the
> worst case can be coming, suppose we need 20000 4K IOVAs at one time. That means
> 10000 IOVAs can be allocated from rcache, but another 10000 IOVAs should be
> allocated from RB tree base on alloc_iova() function. But the RB tree currently
> have at least (9000 + 8500 + 8600 + 9200 + 7000) = 42300 nodes. The average speed
> of RB tree traverse will be very slow. For my test scenario, the 4K size IOVAs are
> frequently used, but others are not. So similarly, when the 20000 4K IOVAs are
> continuous freed, the first 10000 IOVAs can be quickly buffered, but the other
> 10000 IOVAs can not.
>
> Zhen Lei (2):
> iommu/iova: introduce iova_magazine_compact_pfns()
> iommu/iova: enhance the rcache optimization
>
> drivers/iommu/iova.c | 100 +++++++++++++++++++++++++++++++++++++++++++++++----
> include/linux/iova.h | 1 +
> 2 files changed, 95 insertions(+), 6 deletions(-)
>
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prev parent reply other threads:[~2019-08-23 8:15 UTC|newest]
Thread overview: 4+ messages / expand[flat|nested] mbox.gz Atom feed top
2019-08-15 12:11 [PATCH v2 0/2] iommu/iova: enhance the rcache optimization Zhen Lei
2019-08-15 12:11 ` [PATCH v2 1/2] iommu/iova: introduce iova_magazine_compact_pfns() Zhen Lei
2019-08-15 12:11 ` [PATCH v2 2/2] iommu/iova: enhance the rcache optimization Zhen Lei
2019-08-23 8:15 ` Leizhen (ThunderTown) [this message]
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