From: K Prateek Nayak <kprateek.nayak@amd.com>
To: Christian Loehle <christian.loehle@arm.com>,
Ingo Molnar <mingo@redhat.com>,
Peter Zijlstra <peterz@infradead.org>,
Juri Lelli <juri.lelli@redhat.com>,
Vincent Guittot <vincent.guittot@linaro.org>,
Anna-Maria Behnsen <anna-maria@linutronix.de>,
Frederic Weisbecker <frederic@kernel.org>,
Thomas Gleixner <tglx@linutronix.de>
Cc: <linux-kernel@vger.kernel.org>,
Dietmar Eggemann <dietmar.eggemann@arm.com>,
Steven Rostedt <rostedt@goodmis.org>,
Ben Segall <bsegall@google.com>, Mel Gorman <mgorman@suse.de>,
Valentin Schneider <vschneid@redhat.com>,
"Gautham R. Shenoy" <gautham.shenoy@amd.com>,
"Swapnil Sapkal" <swapnil.sapkal@amd.com>,
Shrikanth Hegde <sshegde@linux.ibm.com>,
Chen Yu <yu.c.chen@intel.com>
Subject: Re: [RESEND RFC PATCH v2 28/29] [EXPERIMENTAL] sched/fair: Add a local counter to rate limit task push
Date: Mon, 8 Dec 2025 23:05:25 +0530 [thread overview]
Message-ID: <6236b897-8924-4065-9193-30f8fd2dfda5@amd.com> (raw)
In-Reply-To: <861ae06a-5c9a-47ce-a290-709785b28833@arm.com>
Hello Chris,
On 12/8/2025 6:03 PM, Christian Loehle wrote:
> Just to confirm, but this patch is included when the cover letter mentions "push" for the
> benchmarks?
Yes, this patch is included.
> Did this help the regressions then?
So without this, I was just using tbench as a smoke test - server client
pair sending a very small amount of data and can lead to very short sleep
time.
Up till 64 client there were slight improvements from not rate limiting
but once I hit the fully loaded case, tbench regresses by up to 10%
mostly because of lack of idle targets but also the CPU doesn't hit the
overutilized threshold to cancel push attempts.
CPUs are still considered "nohz" until the first tick hits and at a high
frequency of CPUs going in and out of idle, "sd->shared->nr_idle_cpus"
turned unreliable in my case as a bailout threshold,
With this rate limiting, things are within 2-3% of the baseline.
--
Thanks and Regards,
Prateek
next prev parent reply other threads:[~2025-12-08 17:35 UTC|newest]
Thread overview: 35+ messages / expand[flat|nested] mbox.gz Atom feed top
2025-12-08 9:26 [RESEND RFC PATCH v2 00/29] sched/fair: Push-based load balancing K Prateek Nayak
2025-12-08 9:26 ` [RESEND RFC PATCH v2 01/29] sched/fair: Simplify set_cpu_sd_state_*() with guards K Prateek Nayak
2025-12-08 9:26 ` [RESEND RFC PATCH v2 02/29] sched/fair: Use rq->nohz_tick_stopped in update_nohz_stats() K Prateek Nayak
2025-12-08 9:26 ` [RESEND RFC PATCH v2 03/29] sched/topology: Optimize sd->shared allocation and assignment K Prateek Nayak
2025-12-08 9:26 ` [RESEND RFC PATCH v2 04/29] sched/fair: Simplify the entry condition for update_idle_cpu_scan() K Prateek Nayak
2025-12-08 9:26 ` [RESEND RFC PATCH v2 05/29] sched/fair: Simplity SIS_UTIL handling in select_idle_cpu() K Prateek Nayak
2025-12-08 9:26 ` [RESEND RFC PATCH v2 06/29] cpumask: Introduce for_each_cpu_and_wrap() and bitfield helpers K Prateek Nayak
2025-12-12 21:03 ` Yury Norov
2025-12-08 9:26 ` [RESEND RFC PATCH v2 07/29] sched/fair: Use for_each_cpu_and_wrap() in select_idle_capacity() K Prateek Nayak
2025-12-08 9:26 ` [RESEND RFC PATCH v2 08/29] sched/fair: Use for_each_cpu_and_wrap() in select_idle_cpu() K Prateek Nayak
2025-12-08 9:26 ` [RESEND RFC PATCH v2 09/29] sched/fair: Rotate the CPU resposible for busy load balancing K Prateek Nayak
2025-12-08 9:26 ` [RESEND RFC PATCH v2 10/29] sched/fair: Use xchg() to set sd->nohz_idle state K Prateek Nayak
2025-12-08 9:26 ` [RESEND RFC PATCH v2 11/29] sched/topology: Attach new hierarchy in rq_attach_root() K Prateek Nayak
2025-12-08 9:26 ` [RESEND RFC PATCH v2 12/29] sched/fair: Fixup sd->nohz_idle state during hotplug / cpuset K Prateek Nayak
2025-12-08 9:26 ` [RESEND RFC PATCH v2 13/29] sched/fair: Account idle cpus instead of busy cpus in sd->shared K Prateek Nayak
2025-12-08 9:27 ` [RESEND RFC PATCH v2 14/29] sched/topology: Introduce fallback sd->shared assignment K Prateek Nayak
2025-12-08 9:27 ` [RESEND RFC PATCH v2 15/29] sched/topology: Introduce percpu sd_nohz for nohz state tracking K Prateek Nayak
2025-12-08 9:27 ` [RESEND RFC PATCH v2 16/29] sched/topology: Introduce "nohz_idle_cpus_mask" in sd->shared K Prateek Nayak
2025-12-08 9:27 ` [RESEND RFC PATCH v2 17/29] sched/topology: Introduce "nohz_shared_list" to keep track of sd->shared K Prateek Nayak
2025-12-08 9:27 ` [RESEND RFC PATCH v2 18/29] sched/fair: Reorder the barrier in nohz_balance_enter_idle() K Prateek Nayak
2025-12-08 9:27 ` [RESEND RFC PATCH v2 19/29] sched/fair: Extract the main _nohz_idle_balance() loop into a helper K Prateek Nayak
2025-12-08 9:27 ` [RESEND RFC PATCH v2 20/29] sched/fair: Convert find_new_ilb() to use nohz_shared_list K Prateek Nayak
2025-12-08 9:27 ` [RESEND RFC PATCH v2 21/29] sched/fair: Introduce sched_asym_prefer_idle() for ILB kick K Prateek Nayak
2025-12-08 9:27 ` [RESEND RFC PATCH v2 22/29] sched/fair: Convert sched_balance_nohz_idle() to use nohz_shared_list K Prateek Nayak
2025-12-08 9:27 ` [RESEND RFC PATCH v2 23/29] sched/fair: Remove "nohz.idle_cpus_mask" K Prateek Nayak
2025-12-08 9:27 ` [RESEND RFC PATCH v2 24/29] sched/fair: Optimize global "nohz.nr_cpus" tracking K Prateek Nayak
2025-12-08 9:27 ` [RESEND RFC PATCH v2 25/29] sched/topology: Add basic debug information for "nohz_shared_list" K Prateek Nayak
2025-12-08 9:27 ` [RESEND RFC PATCH v2 26/29] [EXPERIMENTAL] sched/fair: Add push task framework K Prateek Nayak
2025-12-08 9:27 ` [RESEND RFC PATCH v2 27/29] [EXPERIMENTAL] sched/fair: Proactive idle balance using push mechanism K Prateek Nayak
2025-12-08 9:27 ` [RESEND RFC PATCH v2 28/29] [EXPERIMENTAL] sched/fair: Add a local counter to rate limit task push K Prateek Nayak
2025-12-08 12:33 ` Christian Loehle
2025-12-08 17:35 ` K Prateek Nayak [this message]
2025-12-08 9:27 ` [RESEND RFC PATCH v2 29/29] [EXPERIMENTAL] sched/fair: Faster alternate for intra-NUMA newidle balance K Prateek Nayak
2025-12-08 14:04 ` [RESEND RFC PATCH v2 00/29] sched/fair: Push-based load balancing Shrikanth Hegde
2025-12-08 17:36 ` K Prateek Nayak
Reply instructions:
You may reply publicly to this message via plain-text email
using any one of the following methods:
* Save the following mbox file, import it into your mail client,
and reply-to-all from there: mbox
Avoid top-posting and favor interleaved quoting:
https://en.wikipedia.org/wiki/Posting_style#Interleaved_style
* Reply using the --to, --cc, and --in-reply-to
switches of git-send-email(1):
git send-email \
--in-reply-to=6236b897-8924-4065-9193-30f8fd2dfda5@amd.com \
--to=kprateek.nayak@amd.com \
--cc=anna-maria@linutronix.de \
--cc=bsegall@google.com \
--cc=christian.loehle@arm.com \
--cc=dietmar.eggemann@arm.com \
--cc=frederic@kernel.org \
--cc=gautham.shenoy@amd.com \
--cc=juri.lelli@redhat.com \
--cc=linux-kernel@vger.kernel.org \
--cc=mgorman@suse.de \
--cc=mingo@redhat.com \
--cc=peterz@infradead.org \
--cc=rostedt@goodmis.org \
--cc=sshegde@linux.ibm.com \
--cc=swapnil.sapkal@amd.com \
--cc=tglx@linutronix.de \
--cc=vincent.guittot@linaro.org \
--cc=vschneid@redhat.com \
--cc=yu.c.chen@intel.com \
/path/to/YOUR_REPLY
https://kernel.org/pub/software/scm/git/docs/git-send-email.html
* If your mail client supports setting the In-Reply-To header
via mailto: links, try the mailto: link
Be sure your reply has a Subject: header at the top and a blank line
before the message body.
This is a public inbox, see mirroring instructions
for how to clone and mirror all data and code used for this inbox
all inboxes | Powered by JetHome®