Messages in this thread Patch in this message | | | From | Arun KS <> | Date | Wed, 19 Jul 2023 10:36:08 +0530 | Subject | Question on sched_clock |
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Hi,
Kernel’s printk uses local_clock() for timestamps and it is mapped to sched_clock(). Two problems/requirements I see,
One, Kernel’s printk timestamps start from 0, I want to change this to match with actual time since boot. Two, sched_clock() doesn’t account for time spend in low power state(suspend to ram)
Could workout patches to modify these behaviours and found working in my system. But need to hear expert opinion on why this is not done in the upstream.
diff --git a/kernel/time/sched_clock.c b/kernel/time/sched_clock.c index 68d6c1190ac7..b63b2ded5727 100644 --- a/kernel/time/sched_clock.c +++ b/kernel/time/sched_clock.c @@ -190,7 +190,10 @@ sched_clock_register(u64 (*read)(void), int bits, unsigned long rate) /* Update epoch for new counter and update 'epoch_ns' from old counter*/ new_epoch = read(); cyc = cd.actual_read_sched_clock(); - ns = rd.epoch_ns + cyc_to_ns((cyc - rd.epoch_cyc) & rd.sched_clock_mask, rd.mult, rd.shift); + if (!cyc) + ns = cyc_to_ns(new_epoch, new_mult, new_shift) + else + ns = rd.epoch_ns + cyc_to_ns((cyc - rd.epoch_cyc) & rd.sched_clock_mask, rd.mult, rd.shift); cd.actual_read_sched_clock = read;
rd.read_sched_clock = read; @@ -287,7 +290,6 @@ void sched_clock_resume(void) { struct clock_read_data *rd = &cd.read_data[0]; - rd->epoch_cyc = cd.actual_read_sched_clock(); hrtimer_start(&sched_clock_timer, cd.wrap_kt, HRTIMER_MODE_REL_HARD); rd->read_sched_clock = cd.actual_read_sched_clock; } Regards, Arun
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