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Message-ID: <ZkYWbhTOEBu5vUVk@cn10ka>
Date: Thu, 16 May 2024 07:25:39 -0700
From: Tanmay Jagdale <tj@...0ka.smtp.subspace.kernel.org>
To: Will Deacon <will@...nel.org>
CC: Tanmay Jagdale <tanmay@...vell.com>, <robin.murphy@....com>,
<joro@...tes.org>, <nicolinc@...dia.com>, <mshavit@...gle.com>,
<baolu.lu@...ux.intel.com>, <thunder.leizhen@...wei.com>,
<set_pte_at@...look.com>, <smostafa@...gle.com>,
<sgoutham@...vell.com>, <gcherian@...vell.com>, <gakula@...vell.com>,
<jcm@...masters.org>, <linux-arm-kernel@...ts.infradead.org>,
<iommu@...ts.linux.dev>, <linux-kernel@...r.kernel.org>
Subject: Re: [PATCH V3 0/2] iommu/arm-smmu-v3: Add support for ECMDQ register
mode
Hi Will,
On Tue, Apr 30, 2024 at 04:09:50PM +0100, Will Deacon wrote:
> On Thu, Apr 25, 2024 at 07:41:50AM -0700, Tanmay Jagdale wrote:
> > Resending the patches by Zhen Lei <thunder.leizhen@...wei.com> that add
> > support for SMMU ECMDQ feature.
> >
> > Tested this feature on a Marvell SoC by implementing a smmu-test driver.
> > This test driver spawns a thread per CPU and each thread keeps sending
> > map, table-walk and unmap requests for a fixed duration.
> >
> > Using this test driver, we compared ECMDQ vs SMMU with software batching
> > support and saw ~5% improvement with ECMDQ. Performance numbers are
> > mentioned below:
> >
> > Total Requests Average Requests Difference
> > Per CPU wrt ECMDQ
> > -----------------------------------------------------------------
> > ECMDQ 239286381 2991079
> > CMDQ Batch Size 1 228232187 2852902 -4.62%
> > CMDQ Batch Size 32 233465784 2918322 -2.43%
> > CMDQ Batch Size 64 231679588 2895994 -3.18%
> > CMDQ Batch Size 128 233189030 2914862 -2.55%
> > CMDQ Batch Size 256 230965773 2887072 -3.48%
>
> These are pretty small improvements in a targetted micro-benchmark. Do
> you have any real-world numbers showing that this is worthwhile? For
> example, running something like netperf.
We are running benchmarks on the latest kernel with and without ECMDQ.
We will share the performance numbers and observations here.
With Regards,
Tanmay
>
> Will
>
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