| Message ID | 20200715020512.20991-1-leo.yan@linaro.org (mailing list archive) |
|---|---|
| Headers | show |
| Series | arm64: perf: Proper cap_user_time* support | expand |
On Wed, Jul 15, 2020 at 10:05:06AM +0800, Leo Yan wrote: ... > > In this version, there have two changes comparing to Peter's original > patch set [1]: > ... > > [1] https://lkml.org/lkml/2020/5/12/481 > Nitpick: please avoid using https://lkml.org: 1) It's a non-official external service 2) The opaque URLs it uses drop the most important info for uniquely identifying e-mails: the Message-Id. Thus if the site one day goes down, and at times it did, the reference is almost gone forever. Use "https://lkml.kernel.org/r/<message-id>". The link becomes: https://lkml.kernel.org/r/20200512124058.833263033@infradead.org thanks, -- Ahmed S. Darwish Linutronix GmbH
Hi Ahmed, On Wed, Jul 15, 2020 at 07:17:15AM +0200, Ahmed S. Darwish wrote: > On Wed, Jul 15, 2020 at 10:05:06AM +0800, Leo Yan wrote: > ... > > > > In this version, there have two changes comparing to Peter's original > > patch set [1]: > > > ... > > > > [1] https://lkml.org/lkml/2020/5/12/481 > > > > Nitpick: please avoid using https://lkml.org: > > 1) It's a non-official external service > 2) The opaque URLs it uses drop the most important info for uniquely > identifying e-mails: the Message-Id. > > Thus if the site one day goes down, and at times it did, the reference > is almost gone forever. > > Use "https://lkml.kernel.org/r/<message-id>". The link becomes: > > https://lkml.kernel.org/r/20200512124058.833263033@infradead.org Thanks for sharing good practice, later will follow this fashion for using links. Thanks, Leo
This patch set is rebased for Peter's patch set to support cap_user_time/cap_user_time_short ABI for Arm64, and export Arm arch timer counter related parameters from kernel to Perf tool. In this version, there have two changes comparing to Peter's original patch set [1]: The first change is for calculation 'time_zero', in the old patch it used the formula: userpg->time_zero -= (rd->epoch_cyc * rd->mult) >> rd->shift; From the testing, if 'rd->epoch_cyc' is a big counter value, then it's easily to cause overflow issue when multiply by the 'rd->mult'. So in this patch set, it changes to use quot/rem approach for the calculation and can avoid overflow: quot = rd->epoch_cyc >> rd->shift; rem = rd->epoch_cyc & (((u64)1 << rd->shift) - 1); ns = quot * rd->mult + ((rem * rd->mult) >> rd->shift); userpg->time_zero -= ns; The second change is to add new patch 'tools headers UAPI: Update tools's copy of linux/perf_event.h', it's used to update perf tool header so make sure the headers are consistent between kernel and user space. This patch set has been rebased on mainline kernel with the latest commit 11ba468877bb ("Linux 5.8-rc5"); it has been verified with Perf tool for Arm SPE timestamp enabling, the patch set for Arm SPE timestamp enabling will be sent out separately. [1] https://lkml.org/lkml/2020/5/12/481 Leo Yan (1): tools headers UAPI: Update tools's copy of linux/perf_event.h Peter Zijlstra (5): sched_clock: Expose struct clock_read_data arm64: perf: Implement correct cap_user_time arm64: perf: Only advertise cap_user_time for arch_timer perf: Add perf_event_mmap_page::cap_user_time_short ABI arm64: perf: Add cap_user_time_short arch/arm64/kernel/perf_event.c | 59 ++++++++++++++++++++------- include/linux/sched_clock.h | 28 +++++++++++++ include/uapi/linux/perf_event.h | 23 +++++++++-- kernel/time/sched_clock.c | 41 ++++++------------- tools/include/uapi/linux/perf_event.h | 23 +++++++++-- 5 files changed, 126 insertions(+), 48 deletions(-)