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FROMLIST: psi: introduce state_mask to represent stalled psi states

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The psi monitoring patches will need to determine the same states as
record_times().  To avoid calculating them twice, maintain a state mask
that can be consulted cheaply.  Do this in a separate patch to keep the
churn in the main feature patch at a minimum.

This adds 4-byte state_mask member into psi_group_cpu struct which results
in its first cacheline-aligned part becoming 52 bytes long.  Add explicit
values to enumeration element counters that affect psi_group_cpu struct
size.

Link: http://lkml.kernel.org/r/20190124211518.244221-4-surenb@google.com
Signed-off-by: Suren Baghdasaryan <surenb@google.com>
Acked-by: Johannes Weiner <hannes@cmpxchg.org>
Cc: Dennis Zhou <dennis@kernel.org>
Cc: Ingo Molnar <mingo@redhat.com>
Cc: Jens Axboe <axboe@kernel.dk>
Cc: Li Zefan <lizefan@huawei.com>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Tejun Heo <tj@kernel.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Stephen Rothwell <sfr@canb.auug.org.au>

(not upstream yet, latest version published at: https://lore.kernel.org/patchwork/patch/1052414/)

Bug: 127712811
Bug: 129157727
Test: lmkd in PSI mode
Change-Id: I38a1ca3d5c9e6cc3ba39e88c6a9af29ecdc0df5b
Signed-off-by: Suren Baghdasaryan <surenb@google.com>
This commit is contained in:
Suren Baghdasaryan
2019-01-31 10:41:54 +11:00
parent ab74992345
commit ada57da3b1
2 changed files with 25 additions and 13 deletions
Download Patch File Download Diff File Expand all files Collapse all files

29
kernel/sched/psi.c
View File

@@ -213,17 +213,17 @@ static bool test_state(unsigned int *tasks, enum psi_states state)
static void get_recent_times(struct psi_group *group, int cpu, u32 *times)
{
struct psi_group_cpu *groupc = per_cpu_ptr(group->pcpu, cpu);
unsigned int tasks[NR_PSI_TASK_COUNTS];
u64 now, state_start;
enum psi_states s;
unsigned int seq;
int s;
u32 state_mask;
/* Snapshot a coherent view of the CPU state */
do {
seq = read_seqcount_begin(&groupc->seq);
now = cpu_clock(cpu);
memcpy(times, groupc->times, sizeof(groupc->times));
memcpy(tasks, groupc->tasks, sizeof(groupc->tasks));
state_mask = groupc->state_mask;
state_start = groupc->state_start;
} while (read_seqcount_retry(&groupc->seq, seq));
@@ -239,7 +239,7 @@ static void get_recent_times(struct psi_group *group, int cpu, u32 *times)
* (u32) and our reported pressure close to what's
* actually happening.
*/
if (test_state(tasks, s))
if (state_mask & (1 << s))
times[s] += now - state_start;
delta = times[s] - groupc->times_prev[s];
@@ -407,15 +407,15 @@ static void record_times(struct psi_group_cpu *groupc, int cpu,
delta = now - groupc->state_start;
groupc->state_start = now;
if (test_state(groupc->tasks, PSI_IO_SOME)) {
if (groupc->state_mask & (1 << PSI_IO_SOME)) {
groupc->times[PSI_IO_SOME] += delta;
if (test_state(groupc->tasks, PSI_IO_FULL))
if (groupc->state_mask & (1 << PSI_IO_FULL))
groupc->times[PSI_IO_FULL] += delta;
}
if (test_state(groupc->tasks, PSI_MEM_SOME)) {
if (groupc->state_mask & (1 << PSI_MEM_SOME)) {
groupc->times[PSI_MEM_SOME] += delta;
if (test_state(groupc->tasks, PSI_MEM_FULL))
if (groupc->state_mask & (1 << PSI_MEM_FULL))
groupc->times[PSI_MEM_FULL] += delta;
else if (memstall_tick) {
u32 sample;
@@ -436,10 +436,10 @@ static void record_times(struct psi_group_cpu *groupc, int cpu,
}
}
if (test_state(groupc->tasks, PSI_CPU_SOME))
if (groupc->state_mask & (1 << PSI_CPU_SOME))
groupc->times[PSI_CPU_SOME] += delta;
if (test_state(groupc->tasks, PSI_NONIDLE))
if (groupc->state_mask & (1 << PSI_NONIDLE))
groupc->times[PSI_NONIDLE] += delta;
}
@@ -448,6 +448,8 @@ static void psi_group_change(struct psi_group *group, int cpu,
{
struct psi_group_cpu *groupc;
unsigned int t, m;
enum psi_states s;
u32 state_mask = 0;
groupc = per_cpu_ptr(group->pcpu, cpu);
@@ -480,6 +482,13 @@ static void psi_group_change(struct psi_group *group, int cpu,
if (set & (1 << t))
groupc->tasks[t]++;
/* Calculate state mask representing active states */
for (s = 0; s < NR_PSI_STATES; s++) {
if (test_state(groupc->tasks, s))
state_mask |= (1 << s);
}
groupc->state_mask = state_mask;
write_seqcount_end(&groupc->seq);
}