On Thu, May 30, 2019 at 11:23:14PM +0800, Feng Tang wrote:
On Thu, May 30, 2019 at 05:21:40AM -0700, Eric Dumazet wrote:
> On Thu, May 30, 2019 at 3:31 AM Feng Tang <feng.tang(a)intel.com> wrote:
> > On Wed, Apr 03, 2019 at 02:34:36PM +0800, kernel test robot wrote:
> > > Greeting,
> > >
> > > FYI, we noticed a -25.7% regression of netperf.Throughput_Mbps due to
> > >
> > >
> > > commit: 8b27dae5a2e89a61c46c6dbc76c040c0e6d0ed4c ("tcp: add one skb
cache for rx")
> > > https://git.kernel.org/cgit/linux/kernel/git/next/linux-next.git
> > Hi Eric,
> > Could you help to check this? thanks,
> Hmmm... patch is old and had some bugs that have been fixed.
> What numbers do you have with more recent kernels ?
I just run the test with 5.2-rc2, and the regression is still there.
Any hint on this?
From the perf data, the spinlock contention has an obvious increase:
9.28 +7.6 16.91
18.55 +8.6 27.14
And for commit 8b27dae5a2 ("tcp: add one skb cache for rx"), IIUC, it
is not a real cache like the "tx skb cache" patch, and kind of a