On 01/13/2014 07:41 PM, Josh Boyer wrote:
We tried, quite a bit, to try and get the xen stuff backported into the 2.6.32-EL6 kernel, but given the patch overlap was something we cant control and lack the time and technical depth in kernel code to maintain that longer term ( this was essentially Johnny and me, doing this over and above most other things ), it was just easier to go down that route.
I'd be very interested to see a list of commits and corresponding benchmarks for consideration into RHEL.
OK. Those kinds of reasons are what I would expect to drive a divergence from the disto kernel. I'm curious to see how those kinds of situations work out in terms of bug reports and additional maintenance burden.
Secondly, there are quite a few anecdotal pieces on dramatic performance improvements in newer kernels, I know atleast one of the top 5 CDN's ( ie carry > 25Gibt/sec ) that recently switched over from the distro centos kernel to a inhouse 3.10 build for 'network perforamnce'.
In quotes, because repeated questions and pokes in various media have failed to get a reasonable, tangiable, technical response out of them beyond 'network perforamance'.
Interesting. I suppose it's possible but without actually data there's really no way to tell. It might even be that they modified 3.10 themselves to gain that performance and are reluctant to talk about it?
I suppose you don't have any additional details.
We did a ton of performance work for RHEL6.5 and are beating upstream performance in various benchmarks while we have a minimal gap in a few benchmarks. Some of them track down to a difference in how memory accounting is performed. That is of course assuming a stock kernel without any bypass technology such as DPDK or SR-IOV.
Just bumping to 3.10 or 3.12 is not going to be an universal performance booster fix.