From: Peter Zijlstra <peterz@infradead.org>
To: David Stevens <stevensd@google.com>
Cc: Catalin Marinas <catalin.marinas@arm.com>,
Will Deacon <will@kernel.org>, Thomas Gleixner <tglx@kernel.org>,
Ingo Molnar <mingo@redhat.com>, Borislav Petkov <bp@alien8.de>,
Dave Hansen <dave.hansen@linux.intel.com>,
x86@kernel.org, "H . Peter Anvin" <hpa@zytor.com>,
Andrew Morton <akpm@linux-foundation.org>,
Dave Chinner <david@fromorbit.com>, Qi Zheng <qi.zheng@linux.dev>,
Roman Gushchin <roman.gushchin@linux.dev>,
Muchun Song <muchun.song@linux.dev>,
Juri Lelli <juri.lelli@redhat.com>,
Vincent Guittot <vincent.guittot@linaro.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>,
K Prateek Nayak <kprateek.nayak@amd.com>,
Uladzislau Rezki <urezki@gmail.com>,
David Hildenbrand <david@kernel.org>,
Lorenzo Stoakes <ljs@kernel.org>,
"Liam R . Howlett" <liam@infradead.org>,
Vlastimil Babka <vbabka@kernel.org>,
Mike Rapoport <rppt@kernel.org>,
Suren Baghdasaryan <surenb@google.com>,
Michal Hocko <mhocko@suse.com>, Kees Cook <kees@kernel.org>,
Sebastian Andrzej Siewior <bigeasy@linutronix.de>,
Clark Williams <clrkwllms@kernel.org>,
suleiman@google.com, linux-kernel@vger.kernel.org,
linux-arm-kernel@lists.infradead.org, linux-mm@kvack.org,
linux-rt-devel@lists.linux.dev, jstultz@google.com
Subject: Re: [RFC 00/10] Reclaimable kernel stacks
Date: Fri, 28 Aug 2026 14:47:58 +0200 [thread overview]
Message-ID: <20260828124758.GP687043@noisy.programming.kicks-ass.net> (raw)
In-Reply-To: <20260827232948.2520558-1-stevensd@google.com>
On Thu, Aug 27, 2026 at 04:29:38PM -0700, David Stevens wrote:
> On Android, system processes typically have 2000-3000 threads. App
> processes add 1000s more threads on top of this.
WTF ?!? Why does that all spawn *that* many threads? Perhaps work on
reducing that some?
> Tracking blocked state and when it is safe to reclaim a stack is done
> via a series of hooks in the scheduler. The actual reclaim of stacks is
> done asynchronously in a shrinker.
>
> Once a task's stack has been reclaimed, it cannot be rescheduled until
> its stack is repopulated. Although there can be a repopulation fast path
> within the scheduler, reliably allocating memory to repopulate the stack
> requires a fallback path that defers the repopulation and wakeup to a
> workqueue context that can use GFP_KERNEL.
I am really confused. On the one hand you have John working on proxy
execution, with the aim on reducing latencies, and then here you are,
posting something that will introduce basically unbound latencies.
next prev parent reply other threads:[~2026-08-28 12:48 UTC|newest]
Thread overview: 41+ messages / expand[flat|nested] mbox.gz Atom feed top
2026-08-27 23:29 [RFC 00/10] Reclaimable kernel stacks David Stevens
2026-08-27 23:29 ` [RFC 01/10] Add !MEMCG memcg_list_lru_alloc implementation David Stevens
2026-08-27 23:29 ` [RFC 02/10] mm/vmalloc: Skip vmallocinfo NUMA stats for VM_SPARSE David Stevens
2026-08-27 23:29 ` [RFC 03/10] fork: refactor vmap stack alloc/free into helpers David Stevens
2026-08-27 23:29 ` [RFC 04/10] mm: vmalloc: support creating aligned vm areas David Stevens
2026-08-27 23:29 ` [RFC 05/10] fork: allocate reclaimable stacks with VM_SPARSE David Stevens
2026-08-27 23:29 ` [RFC 06/10] Reclaim memory from blocked kernel stacks David Stevens
2026-08-27 23:53 ` sashiko-bot
2026-08-28 11:54 ` Peter Zijlstra
2026-08-28 12:01 ` Peter Zijlstra
2026-08-28 12:04 ` Peter Zijlstra
2026-08-29 0:18 ` David Stevens
2026-08-29 8:39 ` Peter Zijlstra
2026-08-29 8:43 ` Peter Zijlstra
2026-08-28 12:41 ` Peter Zijlstra
2026-08-28 12:57 ` Peter Zijlstra
2026-08-28 23:33 ` David Stevens
2026-08-28 13:36 ` Sebastian Andrzej Siewior
2026-08-28 13:59 ` Peter Zijlstra
2026-08-28 14:25 ` Peter Zijlstra
2026-08-28 15:58 ` Sebastian Andrzej Siewior
2026-08-28 15:10 ` Sebastian Andrzej Siewior
2026-08-28 19:08 ` Steven Rostedt
2026-08-28 19:13 ` Steven Rostedt
2026-08-28 19:17 ` Steven Rostedt
2026-08-28 20:50 ` David Stevens
2026-08-29 8:49 ` Peter Zijlstra
2026-08-29 14:49 ` Matthew Wilcox
2026-08-28 21:17 ` David Stevens
2026-08-27 23:29 ` [RFC 07/10] Reclaim stacks via a shrinker David Stevens
2026-08-27 23:29 ` [RFC 08/10] Set PF_RECLAIMABLE_STACK in various places David Stevens
2026-08-27 23:43 ` sashiko-bot
2026-08-28 6:33 ` K Prateek Nayak
2026-08-27 23:29 ` [RFC 09/10] x86: Enable reclaimable stacks David Stevens
2026-08-27 23:29 ` [RFC 10/10] arm64: " David Stevens
2026-08-28 12:47 ` Peter Zijlstra [this message]
2026-08-28 14:33 ` [RFC 00/10] Reclaimable kernel stacks Steven Rostedt
2026-08-28 14:35 ` Peter Zijlstra
2026-08-28 14:45 ` Peter Zijlstra
2026-08-28 16:10 ` Steven Rostedt
2026-08-28 17:58 ` David Stevens
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=20260828124758.GP687043@noisy.programming.kicks-ass.net \
--to=peterz@infradead.org \
--cc=akpm@linux-foundation.org \
--cc=bigeasy@linutronix.de \
--cc=bp@alien8.de \
--cc=bsegall@google.com \
--cc=catalin.marinas@arm.com \
--cc=clrkwllms@kernel.org \
--cc=dave.hansen@linux.intel.com \
--cc=david@fromorbit.com \
--cc=david@kernel.org \
--cc=dietmar.eggemann@arm.com \
--cc=hpa@zytor.com \
--cc=jstultz@google.com \
--cc=juri.lelli@redhat.com \
--cc=kees@kernel.org \
--cc=kprateek.nayak@amd.com \
--cc=liam@infradead.org \
--cc=linux-arm-kernel@lists.infradead.org \
--cc=linux-kernel@vger.kernel.org \
--cc=linux-mm@kvack.org \
--cc=linux-rt-devel@lists.linux.dev \
--cc=ljs@kernel.org \
--cc=mgorman@suse.de \
--cc=mhocko@suse.com \
--cc=mingo@redhat.com \
--cc=muchun.song@linux.dev \
--cc=qi.zheng@linux.dev \
--cc=roman.gushchin@linux.dev \
--cc=rostedt@goodmis.org \
--cc=rppt@kernel.org \
--cc=stevensd@google.com \
--cc=suleiman@google.com \
--cc=surenb@google.com \
--cc=tglx@kernel.org \
--cc=urezki@gmail.com \
--cc=vbabka@kernel.org \
--cc=vincent.guittot@linaro.org \
--cc=vschneid@redhat.com \
--cc=will@kernel.org \
--cc=x86@kernel.org \
/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