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Date:   Fri, 9 Jul 2021 22:21:39 +0800
From:   Ming Lei <ming.lei@redhat.com>
To:     "Russell King (Oracle)" <linux@armlinux.org.uk>
Cc:     linux-nvme@lists.infradead.org, Will Deacon <will@kernel.org>,
        linux-arm-kernel@lists.infradead.org,
        iommu@lists.linux-foundation.org, linux-kernel@vger.kernel.org
Subject: Re: [bug report] iommu_dma_unmap_sg() is very slow then running IO
 from remote numa node
Message-ID: <YOhbc5C47IzC893B@T590>
References: <YOgK8fdv7dOQtkET@T590>
 <20210709101614.GZ22278@shell.armlinux.org.uk>
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On Fri, Jul 09, 2021 at 11:16:14AM +0100, Russell King (Oracle) wrote:
> On Fri, Jul 09, 2021 at 04:38:09PM +0800, Ming Lei wrote:
> > I observed that NVMe performance is very bad when running fio on one
> > CPU(aarch64) in remote numa node compared with the nvme pci numa node.
> 
> Have you checked the effect of running a memory-heavy process using
> memory from node 1 while being executed by CPUs in node 0?

1) aarch64
[root@ampere-mtjade-04 ~]# taskset -c 0 numactl -m 0  perf bench mem memcpy -s 4GB -f default
# Running 'mem/memcpy' benchmark:
# function 'default' (Default memcpy() provided by glibc)
# Copying 4GB bytes ...

      11.511752 GB/sec
[root@ampere-mtjade-04 ~]# taskset -c 0 numactl -m 1  perf bench mem memcpy -s 4GB -f default
# Running 'mem/memcpy' benchmark:
# function 'default' (Default memcpy() provided by glibc)
# Copying 4GB bytes ...

       3.084333 GB/sec


2) x86_64[1]
[root@hp-dl380g10-01 mingl]#  taskset -c 0 numactl -m 0  perf bench mem memcpy -s 4GB -f default
# Running 'mem/memcpy' benchmark:
# function 'default' (Default memcpy() provided by glibc)
# Copying 4GB bytes ...

       4.193927 GB/sec
[root@hp-dl380g10-01 mingl]#  taskset -c 0 numactl -m 1  perf bench mem memcpy -s 4GB -f default
# Running 'mem/memcpy' benchmark:
# function 'default' (Default memcpy() provided by glibc)
# Copying 4GB bytes ...

       3.553392 GB/sec


[1] on this x86_64 machine, IOPS can reach 680K in same fio nvme test 


Thanks,
Ming