[ovs-dev] [PATCH] coverage: Add coverage_try_clear() for performance-critical threads.

Alex Wang alexw at nicira.com
Tue Aug 25 23:22:44 UTC 2015


Apologize for the delay, applied to master~

On Tue, Aug 25, 2015 at 4:53 AM, Traynor, Kevin <kevin.traynor at intel.com>
wrote:

>
> > -----Original Message-----
> > From: dev [mailto:dev-bounces at openvswitch.org] On Behalf Of Daniele Di
> > Proietto
> > Sent: Monday, August 24, 2015 7:08 PM
> > To: Alex Wang
> > Cc: dev; Ilya Maximets
> > Subject: Re: [ovs-dev] [PATCH] coverage: Add coverage_try_clear() for
> > performance-critical threads.
> >
> > Hi Alex,
> >
> > sorry for the delay and thanks for taking care of this.
> > I couldn't experience any noticeable performance drop.
>
> Same for me - no performance drop in my tests.
>
> >
> > Acked-by: Daniele Di Proietto <diproiettod at vmware.com>
> >
> > On 22/08/2015 16:44, "Alex Wang" <alexw at nicira.com> wrote:
> >
> > >Sorry for the delay of pushing this and related dpdk patches,
> > >
> > >Want to spend some time next week measuring the performance impact,~
> > >
> > >Thanks,
> > >Alex Wang,
> > >
> > >On Fri, Aug 21, 2015 at 12:48 PM, Ben Pfaff <blp at nicira.com> wrote:
> > >
> > >> On Thu, Aug 13, 2015 at 11:48:49AM -0700, Alex Wang wrote:
> > >> > For performance-critical threads like pmd threads, we currently make
> > >>them
> > >> > never call coverage_clear() to avoid contention over the global
> mutex
> > >> > 'coverage_mutex'.  So, even though pmd thread still keeps updating
> > >>their
> > >> > thread-local coverage count, the count is never attributed to the
> > >>global
> > >> > total.  But it is useful to have them available.
> > >> >
> > >> > This commit makes this happen by implementing a non-contending
> version
> > >> > of the clear function, coverage_try_clear().  The function will use
> > >> > the ovs_mutex_trylock() and return immediately if the mutex cannot
> > >> > be acquired.  Since threads like pmd thread are always busy-looping,
> > >> > the lock will eventually be acquired.
> > >> >
> > >> > Requested-by: Ilya Maximets <i.maximets at samsung.com>
> > >> > Signed-off-by: Alex Wang <alexw at nicira.com>
> > >>
> > >> This seems like an improvement.  I can imagine better data structures
> > >> but I don't know whether they're worthwhile.
> > >>
> > >> Acked-by: Ben Pfaff <blp at nicira.com>
> > >>
> > >_______________________________________________
> > >dev mailing list
> > >dev at openvswitch.org
> > >
> https://urldefense.proofpoint.com/v2/url?u=http-3A__openvswitch.org_mailma
> >
> >n_listinfo_dev&d=BQIGaQ&c=Sqcl0Ez6M0X8aeM67LKIiDJAXVeAw-YihVMNtXt-uEs&r=Sm
> >
> >B5nZacmXNq0gKCC1s_Cw5yUNjxgD4v5kJqZ2uWLlE&m=eyhC-yvVbYX9Ldi_S7D-WQlI0gxgpN
> > >Z2f7CNpONhdHQ&s=u-Il0-gm4T7RRfs9WlDo_6TRlF2zgHBDAjBYt_IV6VM&e=
> >
> > _______________________________________________
> > dev mailing list
> > dev at openvswitch.org
> > http://openvswitch.org/mailman/listinfo/dev
>



More information about the dev mailing list