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author | Jianfeng Tan <henry.tjf@antfin.com> | 2019-10-08 17:43:01 +0000 |
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committer | Jianfeng Tan <henry.tjf@antfin.com> | 2019-11-23 13:24:46 +0000 |
commit | f697d1a33e4e7cefb4164ec977c38ccc2a228099 (patch) | |
tree | d100fbfa557b1363648600ab8c24cc918671f070 /pkg/sentry/fs/proc/meminfo.go | |
parent | b0a1bbd3e248888cf6c9e6fa73df5d2c22490f85 (diff) |
gofer: reduce CPU usage on GC as of frequent readdir
Refer to golang mallocgc(), each time of allocating an object > 32 KB,
a gc will be triggered.
When we do readdir, sentry always passes 65535, which leads to a malloc
of 65535 * sizeof(p9.Direnta) > 32 KB.
Considering we already use slice append, let's avoid defining the
capability for this slide.
Command for test:
Before this change:
(container)$ time tree linux-5.3.1 > /dev/null
real 0m54.272s
user 0m2.010s
sys 0m1.740s
(CPU usage of Gofer: ~30 cores)
(host)$ perf top -p <pid-of-gofer>
42.57% runsc [.] runtime.gcDrain
23.41% runsc [.] runtime.(*lfstack).pop
9.74% runsc [.] runtime.greyobject
8.06% runsc [.] runtime.(*lfstack).push
4.33% runsc [.] runtime.scanobject
1.69% runsc [.] runtime.findObject
1.12% runsc [.] runtime.findrunnable
0.69% runsc [.] runtime.runqgrab
...
(host)$ mkdir test && cd test
(host)$ for i in `seq 1 65536`; do mkdir $i; done
(container)$ time ls test/ > /dev/null
real 2m10.934s
user 0m0.280s
sys 0m4.260s
(CPU usage of Gofer: ~1 core)
After this change:
(container)$ time tree linux-5.3.1 > /dev/null
real 0m22.465s
user 0m1.270s
sys 0m1.310s
(CPU usage of Gofer: ~1 core)
$ perf top -p <pid-of-gofer>
20.57% runsc [.] runtime.gcDrain
7.15% runsc [.] runtime.(*lfstack).pop
4.11% runsc [.] runtime.scanobject
3.78% runsc [.] runtime.greyobject
2.78% runsc [.] runtime.(*lfstack).push
...
(host)$ mkdir test && cd test
(host)$ for i in `seq 1 65536`; do mkdir $i; done
(container)$ time ls test/ > /dev/null
real 0m13.338s
user 0m0.190s
sys 0m3.980s
(CPU usage of Gofer: ~0.8 core)
Fixes #898
Signed-off-by: Jianfeng Tan <henry.tjf@antfin.com>
Diffstat (limited to 'pkg/sentry/fs/proc/meminfo.go')
0 files changed, 0 insertions, 0 deletions