Messages in this thread | | | Subject | Re: [PATCH v3 00/20] Speculative page faults | From | Laurent Dufour <> | Date | Thu, 28 Sep 2017 14:17:22 +0200 |
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Hi,
On 26/09/2017 01:34, Andrew Morton wrote: > On Mon, 25 Sep 2017 09:27:43 -0700 Alexei Starovoitov <alexei.starovoitov@gmail.com> wrote: > >> On Mon, Sep 18, 2017 at 12:15 AM, Laurent Dufour >> <ldufour@linux.vnet.ibm.com> wrote: >>> Despite the unprovable lockdep warning raised by Sergey, I didn't get any >>> feedback on this series. >>> >>> Is there a chance to get it moved upstream ? >> >> what is the status ? >> We're eagerly looking forward for this set to land, >> since we have several use cases for tracing that >> will build on top of this set as discussed at Plumbers. > > There has been sadly little review and testing so far :(
I do agree and I could just encourage people to do so :/
> I'll be taking a close look at it all over the next couple of weeks.
Thanks Andrew for giving it a close look.
> One terribly important thing (especially for a patchset this large and > intrusive) is the rationale for merging it: the justification, usually > in the form of end-user benefit.
The benefit is only for multi-threaded processes. But even on *small* systems with 16 CPUs, there is a real benefit.
> > Laurent's [0/n] provides some nice-looking performance benefits for > workloads which are chosen to show performance benefits(!) but, alas, > no quantitative testing results for workloads which we may suspect will > be harmed by the changes(?).
I did test with kernbench, involving gcc/ld which are not multi-threaded, AFAIK, and I didn't see any impact. But if you know additional test I should give a try, please advise.
Regarding ebizzy, it was designed to simulate web server's activity, so I guess there will be improvements when running real web servers.
> Even things as simple as impact upon > single-threaded pagefault-intensive workloads and its effect upon > CONFIG_SMP=n .text size? > > If you have additional usecases then please, spell them out for us in > full detail so we can better understand the benefits which this > patchset provides.
The other use-case I'm aware of is on memory database, where performance improvements is really significant, as I mentioned in the header of my series.
Cheers, Laurent.
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