From: linhaifeng <haifeng.lin@huawei.com>
To: <nyc@holomorphy.com>, <tglx@linutronix.de>, <mingo@redhat.com>,
<hpa@zytor.com>
Cc: <linux-kernel@vger.kernel.org>
Subject: LLC cache miss increases with the increases of hugepages
Date: Mon, 6 Mar 2017 10:53:06 +0800 [thread overview]
Message-ID: <58BCCF12.40804@huawei.com> (raw)
Hi，
I did a network forward test with ovs-dpdk, and found that LLC cache miss
increases with the increases of hugepages. ovs-dpdk only use 4 hugepages,
hugepage size is 1G.Why LLC cache miss increases ? I just echo more hugepages
but haven't been used yet.
some informations:
CPU: Intel(R) Xeon(R) CPU E5-2620 v3@ 2.40GHz
L1d cache: 32K
L1i cache: 32K
L2 cache: 256K
L3 cache: 15360K
echo 10 > /proc/sys/vm/nr_hugepages
ovs-dpdk's LLC-load-misses:3.88%
ovs-dpdk's iTLB-load-misses: 4.37%
echo 100 > /proc/sys/vm/nr_hugepages
reboot VM restart test.
ovs-dpdk's LLC-load-misses:31.55%
ovs-dpdk's iTLB-load-misses: 36.36%
I use perf to watch LLC-loads when not run test:
Samples: 1M of event 'LLC-loads', Event count (approx.): 57240206
Overhead Shared Object Symbol
9.19% [kernel] [k] copy_page_rep
5.03% [kernel] [k] ktime_get
4.06% [unknown] [.] 0x000000000043e39d
2.65% bash [.] 0x000000000003e39d
2.13% [kernel] [k] rcu_check_callbacks
The function copy_page_rep seems like would prefetch all hugepages?
reply other threads:[~2017-03-06 3:00 UTC|newest]
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