> -----Original Message----- > From: David Miller [mailto:davem@xxxxxxxxxxxxx] > Sent: Wednesday, May 27, 2015 11:13 AM > To: KY Srinivasan > Cc: netdev@xxxxxxxxxxxxxxx; linux-kernel@xxxxxxxxxxxxxxx; > devel@xxxxxxxxxxxxxxxxxxxxxx; olaf@xxxxxxxxx; apw@xxxxxxxxxxxxx; > jasowang@xxxxxxxxxx > Subject: Re: [PATCH net-next 1/1] hv_netvsc: Properly size the vrss queues > > From: "K. Y. Srinivasan" <kys@xxxxxxxxxxxxx> > Date: Tue, 26 May 2015 16:21:09 -0700 > > > The current algorithm for deciding on the number of VRSS channels is > > not optimal since we open up the min of number of CPUs online and the > > number of VRSS channels the host is offering. So on a 32 VCPU guest > > we could potentially open 32 VRSS subchannels. Experimentation has > > shown that it is best to limit the number of VRSS channels to the number > > of CPUs within a NUMA node. As part of this work introduce a module > > parameter to control the number of sub-channels we would open up as > well. > > Here is the new algorithm for deciding on the number of sub-channels we > > would open up: > > 1) Pick the minimum of what the host is offering and what the driver > > in the guest is specifying via the module parameter. > > 2) Pick the minimum of (1) and the numbers of CPUs in the NUMA > > node the primary channel is bound to. > > > > Signed-off-by: K. Y. Srinivasan <kys@xxxxxxxxxxxxx> > > No new module parameters, sorry. > > You will have to make it such that this can be changed at run time, > and use a generic run-time mechanism to configure this value that any > driver can use. > > I will not accept: "this is not possible" or "this is too hard" as a > reason why you have to use a module parameter. > > Settings that cannot be set at run time are painful for people who run > large scale operations where resetting entire systems to change a > setting is completely and utterly impractical. Agreed; we are working on full ethtool support to address this very issue. The module parameter that I introduced here was just a temporary solution until the full ethtool support. I will get rid of the module parameter and resubmit this patch. Regards, K. Y _______________________________________________ devel mailing list devel@xxxxxxxxxxxxxxxxxxxxxx http://driverdev.linuxdriverproject.org/mailman/listinfo/driverdev-devel
