Adding a new VFS Lttng module for performance testing
slow at samba.org
Mon Dec 17 16:50:52 UTC 2018
sorry, looks like we dropped the ball on this one.
On Wed, Oct 24, 2018 at 12:04:03PM +0800, deanraccoon wrote:
>I think syscalls only works for local file system. When I was tuning the samba
>ceph/glusterfs module. Neither systemtap nor bpf could help me.
ah, I see. Well, you can trace arbitray functions with Systemtap, but after some
more research I see another argument for having the ltt-ng VFS module. With
Systemtap every enabled tracepoint that is excersized triggers a context switch
as all metrics are gathered in the kernel by Systemtap. As a result for large
number of enabled trace points (think: all syscalls) the performance impact on
the process becomes significant.
With ltt-ng by contrast the metrics are collected in userspace so the costly
context switch is avoided.
Can you send us an updated patchset on top of current master? We'll also need a
manpage. I'll happily review and will help getting this integrated.
Ralph Boehme, Samba Team https://samba.org/
Samba Developer, SerNet GmbH https://sernet.de/en/samba/
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