On Tue, Dec 31, 2024 at 9:56 AM fuqiang wang <[email protected]> wrote:
> The current dirtylimit_throttle_pct trace event is triggered when the > throttle time is adjusted linearly. Modify the trace event so that it > can record non-linear adjustments. Please target the optimization mentioned above in a single patch. . > Additionally, since the throttle time > might be adjusted again at the end of the dirtylimit_set_throttle > function, move the trace event to after this process and calculate the > final adjustment time and sleep percent. > If need, I'd advise dividing this into a different patch. > > This patch can fix the following issue: > > 1. The current dirty rate at 1000MB/s and the dirty limit value at > 10000MB/s, before merge this patch, this trace event will print: > > CPU[2] throttle percent: 98, throttle adjust time 191590 us > CPU[2] throttle percent: 98, throttle adjust time 191002 us > CPU[2] throttle percent: 98, throttle adjust time 191002 us > > After merge this patch, there will be no print. > > 2. The current dirty rate is 1000MB/s and the dirty limit rate value is > 333MB/s, before merge this patch, this trace event will print: > > CPU[3] throttle percent: 98, throttle adjust time 32666634 us > > It will only print linear adjustment, and the adjust time > will be larger and only have positive values. > > After merge this patch, print as following: > CPU[2] throttle percent: 97, throttle adjust time 128766 us > CPU[2] throttle percent: 94, throttle adjust time -61131 us > CPU[2] throttle percent: 92, throttle adjust time -16634 us > ... > CPU[2] throttle percent: 74, throttle adjust time -390 us > CPU[2] throttle percent: 73, throttle adjust time -390 us > > Signed-off-by: wangfuqiang49 <[email protected]> > --- > system/dirtylimit.c | 28 ++++++++++++++++++++-------- > 1 file changed, 20 insertions(+), 8 deletions(-) > > diff --git a/system/dirtylimit.c b/system/dirtylimit.c > index 7c071248bb..c7f663e5b9 100644 > --- a/system/dirtylimit.c > +++ b/system/dirtylimit.c > @@ -281,31 +281,30 @@ static void dirtylimit_set_throttle(CPUState *cpu, > { > int64_t ring_full_time_us = 0; > uint64_t sleep_pct = 0; > + uint64_t throttle_pct = 0; > uint64_t throttle_us = 0; > + int64_t throtlle_us_old = cpu->throttle_us_per_full; > > if (current == 0) { > cpu->throttle_us_per_full = 0; > - return; > + goto end; > The current dirty rate is zero, indicating nothing needs to be done, including displaying the trace event. return directly seems justified. > } > > ring_full_time_us = dirtylimit_dirty_ring_full_time(current); > > if (dirtylimit_need_linear_adjustment(quota, current)) { > if (quota < current) { > - sleep_pct = (current - quota) * 100 / current; > s/sleep_pct/throttle_pci/ , why ? > + throttle_pct = (current - quota) * 100 / current; > throttle_us = > - ring_full_time_us * sleep_pct / (double)(100 - sleep_pct); > + ring_full_time_us * throttle_pct / (double)(100 - > throttle_pct); > cpu->throttle_us_per_full += throttle_us; > } else { > - sleep_pct = (quota - current) * 100 / quota; > + throttle_pct = (quota - current) * 100 / quota; > throttle_us = > - ring_full_time_us * sleep_pct / (double)(100 - sleep_pct); > + ring_full_time_us * throttle_pct / (double)(100 - > throttle_pct); > cpu->throttle_us_per_full -= throttle_us; > } > > - trace_dirtylimit_throttle_pct(cpu->cpu_index, > - sleep_pct, > - throttle_us); > } else { > if (quota < current) { > cpu->throttle_us_per_full += ring_full_time_us / 10; > @@ -323,6 +322,19 @@ static void dirtylimit_set_throttle(CPUState *cpu, > ring_full_time_us * DIRTYLIMIT_THROTTLE_PCT_MAX); > > cpu->throttle_us_per_full = MAX(cpu->throttle_us_per_full, 0); > + > +end: > + if (cpu->throttle_us_per_full - throtlle_us_old) { > + if (current) { > + sleep_pct = ring_full_time_us * 100 / (ring_full_time_us + > + cpu->throttle_us_per_full); > + } else { > + sleep_pct = 0; > + } > + trace_dirtylimit_throttle_pct(cpu->cpu_index, > + sleep_pct, > + cpu->throttle_us_per_full - > + throtlle_us_old); } > This changes the interface of the trace event, We can keep the throttle_us and add the delta meanwhile: trace_dirtylimit_throttle_pct(cpu->cpu_index, sleep_pct, throttle_us, cpu->throttle_us_per_full - throtlle_us_old) } > > static void dirtylimit_adjust_throttle(CPUState *cpu) > -- > 2.47.0 > > -- Best regards
