From: Peter Zijlstra <peterz@infradead.org>
To: Christophe Leroy <christophe.leroy@csgroup.eu>
Cc: Song Liu <song@kernel.org>,
"linux-modules@vger.kernel.org" <linux-modules@vger.kernel.org>,
"linux-kernel@vger.kernel.org" <linux-kernel@vger.kernel.org>,
"songliubraving@fb.com" <songliubraving@fb.com>,
Luis Chamberlain <mcgrof@kernel.org>,
Thomas Gleixner <tglx@linutronix.de>
Subject: Re: [PATCH/RFC] module: replace module_layout with module_memory
Date: Wed, 18 Jan 2023 16:07:17 +0100 [thread overview]
Message-ID: <Y8gLJYA3ibA8De58@hirez.programming.kicks-ass.net> (raw)
In-Reply-To: <154ed99c-5877-35f6-5e7d-9d7abada7d33@csgroup.eu>
On Tue, Jan 10, 2023 at 06:31:41AM +0000, Christophe Leroy wrote:
> Le 09/01/2023 à 21:51, Song Liu a écrit :
> > Do you mean one tree will cause addr_[min|max] to be inaccurate?
> >
>
> Yes at least. On powerpc you will have module text below kernel,
> somewhere between 0xb0000000 and 0xcfffffff, and you will have module
> data in vmalloc area, somewhere between 0xf0000000 and 0xffffffff.
>
> If you have only one tree, any address between 0xc0000000 and 0xefffffff
> will trigger a tree search.
The current min/max thing is tied to the tree because of easy update on
remove, but module-insert/remove is not a performance critical path.
So I think it should be possible to have {min,max}[TYPES] pairs. Either
brute force the removal -- using a linear scan of the mod->list to find
the new bounds on removal.
Or overengineer the whole thing and use an augmented tree to keep that
many heaps in sync during the update -- but this seems total overkill.
The only consideration is testing that many ranges in
__module_address(), this is already 2 cachelines worth of range-checks
-- which seems a little excessive.
(also, I note that module_addr_{min,max} are unused these days)
next prev parent reply other threads:[~2023-01-18 15:07 UTC|newest]
Thread overview: 18+ messages / expand[flat|nested] mbox.gz Atom feed top
2023-01-06 22:09 [PATCH/RFC] module: replace module_layout with module_memory Song Liu
2023-01-09 18:03 ` Christophe Leroy
2023-01-09 18:24 ` Song Liu
2023-01-09 20:51 ` Song Liu
2023-01-10 6:31 ` Christophe Leroy
2023-01-10 6:51 ` Song Liu
2023-01-18 15:07 ` Peter Zijlstra [this message]
2023-01-18 17:52 ` Song Liu
2023-01-10 18:31 ` Song Liu
2023-01-17 18:50 ` Song Liu
2023-01-18 7:40 ` Christoph Hellwig
2023-01-18 17:37 ` Song Liu
2023-01-18 21:52 ` Song Liu
2023-01-19 5:35 ` Christoph Hellwig
2023-01-19 8:29 ` Song Liu
2023-01-20 17:42 ` Song Liu
2023-01-23 6:57 ` Christoph Hellwig
2023-01-24 18:01 ` Song Liu
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