[PATCH v2] Revert "sched: enable traffic class oversubscription unconditionally"

[Singh, Jasvinder]

> -----Original Message-----
> From: Dumitrescu, Cristian <cristian.dumitrescu at intel.com>
> Sent: Tuesday, March 15, 2022 5:25 PM
> To: Thomas Monjalon <thomas at monjalon.net>; Ajmera, Megha
> <megha.ajmera at intel.com>
> Cc: dev at dpdk.org; Mcnamara, John <john.mcnamara at intel.com>; Singh,
> Jasvinder <jasvinder.singh at intel.com>; Thakur, Sham Singh
> <sham.singh.thakur at intel.com>; david.marchand at redhat.com
> Subject: RE: [PATCH v2] Revert "sched: enable traffic class oversubscription
> unconditionally"
> 
> Hi Thomas,
> 
> > -----Original Message-----
> > From: Thomas Monjalon <thomas at monjalon.net>
> > Sent: Tuesday, March 15, 2022 11:23 AM
> > To: Ajmera, Megha <megha.ajmera at intel.com>
> > Cc: dev at dpdk.org; Mcnamara, John <john.mcnamara at intel.com>; Singh,
> > Jasvinder <jasvinder.singh at intel.com>; Dumitrescu, Cristian
> > <cristian.dumitrescu at intel.com>; Thakur, Sham Singh
> > <sham.singh.thakur at intel.com>; david.marchand at redhat.com
> > Subject: Re: [PATCH v2] Revert "sched: enable traffic class
> > oversubscription unconditionally"
> >
> > 14/03/2022 13:27, Megha Ajmera:
> > > This reverts commit d91c4b1bb5a938734fe8e66da8f965304919f38e.
> > >
> > > When enabling TC OV unconditionally, it is observed the performance
> > > drops by ~20% hence reverting this commit.
> > >
> > > Fixes: d91c4b1bb5a9 ("sched: enable traffic class oversubscription
> > > unconditionally")
> > >
> > > Signed-off-by: Megha Ajmera <megha.ajmera at intel.com>
> >
> > Repeating what was suggested yesterday in a private email.
> > Sorry Megha, I don't know why you were not Cc'ed by your Intel
> colleagues.
> >
> > David and I suggested to drop the code which was enabled by the
> > compilation flag RTE_SCHED_SUBPORT_TC_OV, which was kind of dead
> code
> > before enabling it unconditionally.
> > This way you maintain the performance of the default compilation, and
> > you can re-introduce the feature, if proven useful, in the next
> > release with a runtime option.
> >
> >
> 
> After talking with Jasvinder and a few other folks, we think the best option at
> this point is to keep the code as it is now in the repository, so no further
> change at this point.
> 
> There is a small performance glitch that we plan to fix shortly after the 22.03
> release by making the Traffic Class Oversubscription feature conditionally
> enabled at run-time as opposed to enabled unconditionally. Megha already
> sent a patch on this, which is under review.
> 
> Is this OK with you?
> 
> Thank you for your help, we don't want to delay the release in any way!
> 
> Regards,
> Cristian

+1