Hi Sudeep,
On Thu, May 09, 2019 at 03:13:50PM +0100, Sudeep Holla wrote:
> On Thu, May 09, 2019 at 11:35:59AM +0100, Sudeep Holla wrote:
> > On Thu, May 09, 2019 at 10:28:11AM +0100, Will Deacon wrote:
>
> [...]
>
> > >
> > > Since SPE uses virtual addressing, we don't really care about the underlying
> > > page layout so there's no need to use higher-order allocations. I suppose we
> > > could theoretically map them at the pmd level in some cases, but ignoring
> > > them should also be harmless and I suspect you can delete the check.
> > >
> >
> > Yes, I did a quick look to see if we can do that, but couldn't find a clue.
> > Not sure if that's any optimisation, we can use order from page_private
> > and set the values accordingly ?
> >
> And I forgot to add the diff that I mentioned above, something like the
> patch below.
>
> Regards,
> Sudeep
>
> -->8
>
> diff --git i/drivers/perf/arm_spe_pmu.c w/drivers/perf/arm_spe_pmu.c
> index 7cb766dafe85..45cd62517080 100644
> --- i/drivers/perf/arm_spe_pmu.c
> +++ w/drivers/perf/arm_spe_pmu.c
> @@ -827,7 +827,7 @@ static void arm_spe_pmu_read(struct perf_event *event)
> static void *arm_spe_pmu_setup_aux(struct perf_event *event, void **pages,
> int nr_pages, bool snapshot)
> {
> - int i, cpu = event->cpu;
> + int i, j, cpu = event->cpu;
> struct page **pglist;
> struct arm_spe_pmu_buf *buf;
>
> @@ -859,11 +859,12 @@ static void *arm_spe_pmu_setup_aux(struct perf_event *event, void **pages,
> struct page *page = virt_to_page(pages[i]);
>
> if (PagePrivate(page)) {
> - pr_warn("unexpected high-order page for auxbuf!");
> - goto out_free_pglist;
> + for (j = 0; j < 1 << page_private(page); j++)
> + pglist[i + j] = page++;
> + i += j - 1;
> + } else {
> + pglist[i] = page;
Hmm. Given that vmap() doesn't do anything special for high-order pages
and rb_alloc_aux()/rb_alloc_aux_page() already split the allocation up
for the page array, what does your change accomplish on top of that?
Will
