On Wed, May 08, 2019 at 05:35:51PM +0800, Hanjun Guo wrote: > +Cc Alexander. > > On 2019/5/8 1:58, Jeremy Linton wrote: > > Hi, > > > > On 5/4/19 6:06 AM, Hanjun Guo wrote: > >> Hi Jeremy, Mark, > >> > >> On 2019/5/4 7:24, Jeremy Linton wrote: > >>> This patch series enables the Arm Statistical Profiling > >>> Extension (SPE) on ACPI platforms. > >>> > >>> This is possible because ACPI 6.3 uses a previously > >>> reserved field in the MADT to store the SPE interrupt > >>> number, similarly to how the normal PMU is described. > >>> If a consistent valid interrupt exists across all the > >>> cores in the system, a platform device is registered. > >>> That then triggers the SPE module, which runs as normal. > >>> > >>> We also add the ability to parse the PPTT for IDENTICAL > >>> cores. We then use this to sanity check the single SPE > >>> device we create. This creates a bit of a problem with > >>> respect to the specification though. The specification > >>> says that its legal for multiple tree's to exist in the > >>> PPTT. We handle this fine, but what happens in the > >>> case of multiple tree's is that the lack of a common > >>> node with IDENTICAL set forces us to assume that there > >>> are multiple non-IDENTICAL cores in the machine. > >> > >> 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 ? -- Regards, Sudeep
