On Mon, Jun 07, 2021 at 09:15:20AM +0800, huang...@chinatelecom.cn wrote:
> +static void calculate_dirtyrate_vcpu(struct DirtyRateConfig config)
> +{
> + CPUState *cpu;
> + int64_t msec = 0;
> + int64_t start_time;
> + uint64_t dirtyrate = 0;
> + uint64_t dirtyrate_sum = 0;
> + int nvcpu = 0;
> + int i = 0;
> +
> + CPU_FOREACH(cpu) {
> + nvcpu++;
> + }
> +
> + dirty_pages = g_malloc0(sizeof(*dirty_pages) * nvcpu);
> +
> + dirtyrate_global_dirty_log_start();
> +
> + CPU_FOREACH(cpu) {
> + record_dirtypages(cpu, true);
> + }
> +
> + DirtyStat.method.vcpu.nvcpu = nvcpu;
> + if (last_method != CALC_DIRTY_RING) {
> + DirtyStat.method.vcpu.rates =
> + g_malloc0(sizeof(DirtyRateVcpu) * nvcpu);
> + }
> +
> + start_time = qemu_clock_get_ms(QEMU_CLOCK_REALTIME);
> + DirtyStat.start_time = start_time / 1000;
> +
> + msec = config.sample_period_seconds * 1000;
> + msec = set_sample_page_period(msec, start_time);
> + DirtyStat.calc_time = msec / 1000;
> +
> + CPU_FOREACH(cpu) {
> + record_dirtypages(cpu, false);
> + }
> +
> + dirtyrate_global_dirty_log_stop();
> +
> + for (i = 0; i < DirtyStat.method.vcpu.nvcpu; i++) {
> + dirtyrate = do_calculate_dirtyrate_vcpu(i);
> + DirtyStat.method.vcpu.rates[i].id = i;
> + DirtyStat.method.vcpu.rates[i].dirty_rate = dirtyrate;
> + dirtyrate_sum += dirtyrate;
> + }
> +
> + DirtyStat.dirty_rate = dirtyrate_sum / DirtyStat.method.vcpu.nvcpu;
Why you'd like to divide with nvcpu? Isn't dirtyrate_sum exactly what we want?
As I don't think we care about average per-vcpu dirty rate, but total here.
> + g_free(dirty_pages);
> +}
I did a run with 4G mem VM, alloc 1G and dirty it with 500MB/s, then
- With old way: I got 95MB/s
- With new way: I got 128MB/s
The new way has the output with:
Dirty rate: 128 (MB/s)
vcpu[0], Dirty rate: 0
vcpu[1], Dirty rate: 1
vcpu[2], Dirty rate: 0
vcpu[3], Dirty rate: 511
I think if without the division, it'll be 512MB/s, which is matching the dirty
workload I initiated.
--
Peter Xu
