linux-kernel - Re: [PATCH v9 4/8] kallsyms: introduce sections needed to map symbols to built-in modules

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Message-ID: <87edu4uz7z.fsf@esperi.org.uk>
Date:   Tue, 15 Nov 2022 13:25:04 +0000
From:   Nick Alcock <nick.alcock@...cle.com>
To:     "Leizhen (ThunderTown)" <thunder.leizhen@...wei.com>
Cc:     Nick Alcock <nick.alcock@...cle.com>,
        Luis Chamberlain <mcgrof@...nel.org>, <masahiroy@...nel.org>,
        <linux-modules@...r.kernel.org>, <linux-kernel@...r.kernel.org>,
        <arnd@...db.de>, <akpm@...ux-foundation.org>,
        <eugene.loh@...cle.com>, <kris.van.hees@...cle.com>,
        Steven Rostedt <rostedt@...dmis.org>
Subject: Re: [PATCH v9 4/8] kallsyms: introduce sections needed to map
 symbols to built-in modules

On 15 Nov 2022, Leizhen spake thusly:

> On 2022/11/15 1:04, Nick Alcock wrote:
>> I don't understand the question, sorry. If this is about the number of
>> KALLSYMS invocations in the kernel build, that should be unchanged by
>> this patch. This was an explicit design goal because it's quite slow to
>> run kallsyms more times and I was already feeling guilty about having to
>> bring back the tristate recursion.
>> 
>> I haven't tried it with Zhen Lei's work: will try for the next
>> iteration, as a matter of course after the rebase. (And, looking at the
>> patch series at the top of modules-next, wow is that quite a hefty
>> performance improvement. And a hefty memory usage increase :( I have a
>> horrible feeling that one of my machines won't have enough memory to
>> boot after this goes in, but it was terribly outdated anyway.)
>
> It's only about 500K. It shouldn't be a problem. Your machine boot from flash?

It's more that it only has 1GiB RAM... but it's also wildly obsolete and
I shouldn't be worrying.

(I'm also a bit miffed because people are worrying about 10K of
overhead at the same time as a patch is going in adding half a meg ;)
but that's just me being childish. And I know you can't add overhead
indefinitely or the system turns into a slug, and I know the speedups
from your change are amazing...)

-- 
NULL && (void)