On Fri, Apr 26, 2019 at 12:54:14PM +0200, Sebastian Andrzej Siewior wrote:
On 2019-04-25 12:46:38 [-0700], Paul E. McKenney wrote:
And it doesn't like my (admittedly ancient) QEMU, complaining about not knowing about "x2apic=on,tsc-deadline=on,hypervisor=on,tsc_adjust=on". If I remove these, it works. I will be upgrading soon (famous last words), so what I am going to do is queue the following separate not-for-upstream patch that makes it work on my setup.
Also, the !SMP scenarios get this:
:CONFIG_PARAVIRT_SPINLOCKS=y: improperly set
I ignored that (because there is a CHECK option to ensure that certain options are set).
True enough, but these things are a bit like compiler warnings in that it is good to have a clean run.
Would it make sense to only set this on CONFIG_SMP=y runs? The easy way to do this is to move it from CFcommon to the scenario files not having CONFIG_SMP=n.
(Which is how I am currently running, I should have added.)
having CONFIG_SMP=n. Or would something else work better?
Or am I doing something wrong?
You should also get that warning on ARM for instance since those PARAVIRT SPINLOCKS are only implemented on x86.
OK, so we would want this to only be added for x86 runs.
I have no numbers to compare the performance with and without that option. So we could drop that option or you tell me where to look after a run with/without that option so I can tell if it is worth the effort.
One place to look is in the summary output:
TREE01 ------- 17540 GPs (58.4667/s) [rcu: g130629 f0x0 ]
The "58.4667/s" is the number of grace periods per second. I would be surprised if CONFIG_PARAVIRT_SPINLOCKS made a noticeable difference in grace-period rate (given the natural variation), but you never know.
Thanx, Paul