[Bug 207022] stat() 4 to 16 times slower on FreeBSD/UFS than on Linux/Ext4

[bugzilla-noreply at freebsd.org]

https://bugs.freebsd.org/bugzilla/show_bug.cgi?id=207022

--- Comment #7 from Fabiano Sidler <fabianosidler at swissonline.ch> ---
Following http://www.brendangregg.com/blog/2015-03-10/freebsd-flame-graphs.html
I've done this:
dtrace -x stackframes=100 -n 'profile-197 /arg0/ { @[stack()] = count(); }' -c
./cstat -o out.stacks
./stackcollapse.pl out.stacks | ./flamegraph.pl > out.svg
uploaded to http://imgh.us/out_4.svg

=== snip out.stacks ===


              kernel`cache_lookup+0x21c
              kernel`namei+0x4d4
              kernel`kern_statat_vnhook+0xae
              kernel`sys_stat+0x2d
              kernel`amd64_syscall+0x357
              kernel`0xffffffff80d30a8b
                1

              kernel`cache_lookup+0x53f
              kernel`namei+0x4d4
              kernel`kern_statat_vnhook+0xae
              kernel`sys_stat+0x2d
              kernel`amd64_syscall+0x357
              kernel`0xffffffff80d30a8b
                1

              kernel`acpi_cpu_c1+0x6
              kernel`sched_idletd+0x1d5
              kernel`fork_exit+0x9a
              kernel`0xffffffff80d30cde
               14
=== snap out.stacks ===

I don't see anything helpful in it, but maybe someone else does?

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