On 2019/5/9 18:35, Sudeep Holla wrote: > On Thu, May 09, 2019 at 10:28:11AM +0100, Will Deacon wrote: >> On Wed, May 08, 2019 at 05:51:49PM +0100, Sudeep Holla wrote: >>> On Wed, May 08, 2019 at 05:35:51PM +0800, Hanjun Guo wrote: [...] >>>>>> >>>>>> Adding this patch set on top of latest mainline kernel, >>>>>> and tested on D06 which has the SPE feature, in boot message >>>>>> shows it was probed successfully: >>>>>> >>>>>> arm_spe_pmu arm,spe-v1: probed for CPUs 0-95 [max_record_sz 128, align 4, features 0x7] >>>>>> >>>>>> but when I test it with spe events such as >>>>>> >>>>>> perf record -c 1024 -e arm_spe_0/branch_filter=0/ -o spe ls >>>>>> >>>>>> it fails with: >>>>>> failed to mmap with 12 (Cannot allocate memory), >>>>>> >>>>>> Confirmed that patch [0] is merged and other perf events are working >>>>>> fine. >>>>> >>>>> Its pretty easy to get into the weeds with this driver, does it work with examples like: >>>>> >>>>> https://lkml.org/lkml/2018/1/14/122 >>>> >>>> No, not work at all. >>>> >>>> SPE works on 5.0, but not work after 5.1-rc1, bisected to this commit: >>>> >>>> 5768402fd9c6 perf/ring_buffer: Use high order allocations for AUX buffers optimistically >>>> >>> >>> Indeed this patch breaks SPE. As mentioned in the patch, it uses high >>> order allocations for AUX buffers and SPE PMU setup_aux explicitly >>> fails with the warning "unexpected high-order page for auxbuf!" if >>> it encounters one. >>> >>> I don't know the intention of that check in SPE. Will ? >> >> 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 ? > >> Does the patch below fix the problem? >> > > Yes it should help, I tried exactly the same thing yesterday and it does > fix the issue. Works for me too, thank you Sudeep and Will for looking into this issue. Best Regards Hanjun
