From mboxrd@z Thu Jan 1 00:00:00 1970 From: Suren Baghdasaryan Subject: [PATCH 4/6] psi: introduce state_mask to represent stalled psi states Date: Fri, 14 Dec 2018 09:15:06 -0800 Message-ID: <20181214171508.7791-5-surenb@google.com> References: <20181214171508.7791-1-surenb@google.com> Mime-Version: 1.0 Content-Transfer-Encoding: 8bit Return-path: DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=google.com; s=20161025; h=from:to:cc:subject:date:message-id:in-reply-to:references :mime-version:content-transfer-encoding; bh=YwSYAI43KM10GrnM4hZ3Qtd3y6BkTcR7ZHO9M+skX2s=; b=akXIWndiUHaos9TbyNLP3xeaC0ZtOOtr3cSf/ilsoUM7WywehoLoqyXEZzuFIORB9M OvxzyeHc32Q4lx447L/4jMQROuD8Tpifnb+eTjanco+ff7o+IwZScCVw5XFu71NXZHQx h65SJNlG1uCZ+LcxQFWTzPj27rLKDsz7X5nBwYOPjf33icL9nUeUcN8H4DxeA2dJ2CoJ u04GoPkgs3B2NaoDOzsMLnvT61RyHEVW0r29CnBfMfhJUd+xuXxPuur/lVVYkfCIPun7 /axdZ+sXYAdccL5hZ+AL8HqqFeX7QG3R9jGqHbyBu5W6pW9dZ01ISpGwMqGQkIolMen/ 1COA== In-Reply-To: <20181214171508.7791-1-surenb@google.com> Sender: linux-kernel-owner@vger.kernel.org List-ID: Content-Type: text/plain; charset="us-ascii" To: gregkh@linuxfoundation.org Cc: tj@kernel.org, lizefan@huawei.com, hannes@cmpxchg.org, axboe@kernel.dk, dennis@kernel.org, dennisszhou@gmail.com, mingo@redhat.com, peterz@infradead.org, akpm@linux-foundation.org, corbet@lwn.net, cgroups@vger.kernel.org, linux-mm@kvack.org, linux-doc@vger.kernel.org, linux-kernel@vger.kernel.org, kernel-team@android.com, Suren Baghdasaryan 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. Signed-off-by: Suren Baghdasaryan --- include/linux/psi_types.h | 3 +++ kernel/sched/psi.c | 29 +++++++++++++++++++---------- 2 files changed, 22 insertions(+), 10 deletions(-) diff --git a/include/linux/psi_types.h b/include/linux/psi_types.h index 2cf422db5d18..2c6e9b67b7eb 100644 --- a/include/linux/psi_types.h +++ b/include/linux/psi_types.h @@ -53,6 +53,9 @@ struct psi_group_cpu { /* States of the tasks belonging to this group */ unsigned int tasks[NR_PSI_TASK_COUNTS]; + /* Aggregate pressure state derived from the tasks */ + u32 state_mask; + /* Period time sampling buckets for each state of interest (ns) */ u32 times[NR_PSI_STATES]; diff --git a/kernel/sched/psi.c b/kernel/sched/psi.c index d2b9c9a1a62f..153c0624976b 100644 --- a/kernel/sched/psi.c +++ b/kernel/sched/psi.c @@ -212,17 +212,17 @@ 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)); @@ -238,7 +238,7 @@ 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]; @@ -390,15 +390,15 @@ 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; @@ -419,10 +419,10 @@ 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; } @@ -431,6 +431,8 @@ 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); @@ -463,6 +465,13 @@ 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); } -- 2.20.0.405.gbc1bbc6f85-goog