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migration/postcopy: Drop all atomic ops in blocktime feature

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Now with the mutex protection it's not needed anymore.

Reviewed-by: Fabiano Rosas <farosas@suse.de>
Link: https://lore.kernel.org/r/20250613141217.474825-4-peterx@redhat.com
Signed-off-by: Peter Xu <peterx@redhat.com>
Signed-off-by: Fabiano Rosas <farosas@suse.de>
This commit is contained in:
Peter Xu 2025-06-13 10:12:06 -04:00 • committed by Fabiano Rosas
parent d2a81ca8c6
commit c0f47dfb5b
1 changed files with 10 additions and 13 deletions
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23
migration/postcopy-ram.c
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@ -849,12 +849,12 @@ void mark_postcopy_blocktime_begin(uintptr_t addr, uint32_t ptid,
low_time_offset = get_low_time_offset(dc);
if (dc->vcpu_addr[cpu] == 0) {
qatomic_inc(&dc->smp_cpus_down);
dc->smp_cpus_down++;
}
qatomic_xchg(&dc->last_begin, low_time_offset);
qatomic_xchg(&dc->page_fault_vcpu_time[cpu], low_time_offset);
qatomic_xchg(&dc->vcpu_addr[cpu], addr);
dc->last_begin = low_time_offset;
dc->page_fault_vcpu_time[cpu] = low_time_offset;
dc->vcpu_addr[cpu] = addr;
/*
* The caller should only inject a blocktime entry when the page is
@ -915,29 +915,26 @@ static void mark_postcopy_blocktime_end(uintptr_t addr)
for (i = 0; i < smp_cpus; i++) {
uint32_t vcpu_blocktime = 0;
read_vcpu_time = qatomic_fetch_add(&dc->page_fault_vcpu_time[i], 0);
if (qatomic_fetch_add(&dc->vcpu_addr[i], 0) != addr ||
read_vcpu_time == 0) {
read_vcpu_time = dc->page_fault_vcpu_time[i];
if (dc->vcpu_addr[i] != addr || read_vcpu_time == 0) {
continue;
}
qatomic_xchg(&dc->vcpu_addr[i], 0);
dc->vcpu_addr[i] = 0;
vcpu_blocktime = low_time_offset - read_vcpu_time;
affected_cpu += 1;
/* we need to know is that mark_postcopy_end was due to
* faulted page, another possible case it's prefetched
* page and in that case we shouldn't be here */
if (!vcpu_total_blocktime &&
qatomic_fetch_add(&dc->smp_cpus_down, 0) == smp_cpus) {
if (!vcpu_total_blocktime && dc->smp_cpus_down == smp_cpus) {
vcpu_total_blocktime = true;
}
/* continue cycle, due to one page could affect several vCPUs */
dc->vcpu_blocktime[i] += vcpu_blocktime;
}
qatomic_sub(&dc->smp_cpus_down, affected_cpu);
dc->smp_cpus_down -= affected_cpu;
if (vcpu_total_blocktime) {
dc->total_blocktime += low_time_offset - qatomic_fetch_add(
&dc->last_begin, 0);
dc->total_blocktime += low_time_offset - dc->last_begin;
}
trace_mark_postcopy_blocktime_end(addr, dc, dc->total_blocktime,
affected_cpu);