From: Sebastian Andrzej Siewior <bigeasy@linutronix.de>
To: Tejun Heo <tj@kernel.org>
Cc: linux-mm@kvack.org, Dennis Zhou <dennis@kernel.org>,
Christoph Lameter <cl@gentwo.org>, Gal Pressman <gal@nvidia.com>,
Peter Zijlstra <peterz@infradead.org>,
Thomas Gleixner <tglx@linutronix.de>
Subject: Re: [PATCH] mm: percpu: Increase PERCPU_MODULE_RESERVE
Date: Wed, 11 Jun 2025 21:06:42 +0200 [thread overview]
Message-ID: <20250611190642.UHcmUwVg@linutronix.de> (raw)
In-Reply-To: <aEnM2VW5fZ5h61wl@slm.duckdns.org>
On 2025-06-11 08:37:13 [-1000], Tejun Heo wrote:
> Yeah but for that, you're making all machines that run the kernel to waste
> two more pages per CPU. Modern machines are big and the overhead quickly
> gets into megs. Sure, it's not a huge amount of memory but it's going to be
> memory that almost nobody uses, relatively speaking, which just sits there
> and gets wasted.
Not sure I waste two pages waste because the memory is allocated once
used.
Anyway, let me redo it to the dynamic allocation then. The memory of the
single module is quite huge. I looked at the per-CPU allocation of all
modules built with a Debian config on x86-64 and (ignoring alignment and
the openvswitch module) it was below 4KiB…
> Thanks.
>
Sebastian
next prev parent reply other threads:[~2025-06-11 19:06 UTC|newest]
Thread overview: 6+ messages / expand[flat|nested] mbox.gz Atom feed top
2025-06-11 16:18 Sebastian Andrzej Siewior
2025-06-11 17:45 ` Tejun Heo
2025-06-11 18:32 ` Sebastian Andrzej Siewior
2025-06-11 18:37 ` Tejun Heo
2025-06-11 19:06 ` Sebastian Andrzej Siewior [this message]
2025-06-11 20:35 ` Tejun Heo
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