On Mon, Apr 23, 2018 at 09:10:33PM +0800, Aaron Lu wrote:

On Mon, Apr 23, 2018 at 11:54:57AM +0300, Tariq Toukan wrote:

quoted

Hi,

I ran my tests with your patches.
Initial BW numbers are significantly higher than I documented back then in
this mail-thread.
For example, in driver #2 (see original mail thread), with 6 rings, I now
get 92Gbps (slightly less than linerate) in comparison to 64Gbps back then.

However, there were many kernel changes since then, I need to isolate your
changes. I am not sure I can finish this today, but I will surely get to it
next week after I'm back from vacation.

Still, when I increase the scale (more rings, i.e. more cpus), I see that
queued_spin_lock_slowpath gets to 60%+ cpu. Still high, but lower than it
used to be.

I wonder if it is on allocation path or free path?

Just FYI, I have pushed two more commits on top of the branch.
They should improve free path zone lock contention for MIGRATE_UNMOVABLE
pages(most kernel code alloc such pages), you may consider apply them if
free path contention is a problem.