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authorJianfeng Tan <henry.tjf@antfin.com>2019-10-08 17:43:01 +0000
committerJianfeng Tan <henry.tjf@antfin.com>2019-11-23 13:24:46 +0000
commitf697d1a33e4e7cefb4164ec977c38ccc2a228099 (patch)
treed100fbfa557b1363648600ab8c24cc918671f070 /pkg/sentry/fs/proc/net.go
parentb0a1bbd3e248888cf6c9e6fa73df5d2c22490f85 (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/net.go')
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