Re: [PATCH v2] log: setlogmask(0) can actually result in a system call, don't use it

[David Gibson <david@gibson.dropbear.id.au>]

[-- Attachment #1: Type: text/plain, Size: 1183 bytes --]

On Sat, Feb 03, 2024 at 12:06:01AM +0100, Stefano Brivio wrote:
> Before commit 32d07f5e59f2 ("passt, pasta: Completely avoid dynamic
> memory allocation"), we didn't store the current log mask in a
> variable, and we fetched it using setlogmask(0) wherever needed.
> 
> But after that commit, we can use our log_mask copy instead. And we
> should: with recent glibc versions, setlogmask(0) actually results in
> a system call, which causes a substantial overhead with high transfer
> rates: we use setlogmask(0) even to decide we don't want to print
> debug messages.
> 
> Now that we rely on log_mask in early stages, before setlogmask() is
> called, we need to initialise that variable to the special LOG_EMERG
> mask value right away: define LOG_EARLY to make this clearer, and,
> while at it, group conditions in vlogmsg() into something more terse.
> 
> Signed-off-by: Stefano Brivio <sbrivio@redhat.com>

Reviewed-by: David Gibson <david@gibson.dropbear.id.au>

-- 
David Gibson			| I'll have my music baroque, and my code
david AT gibson.dropbear.id.au	| minimalist, thank you.  NOT _the_ _other_
				| _way_ _around_!
http://www.ozlabs.org/~dgibson

[-- Attachment #2: signature.asc --]
[-- Type: application/pgp-signature, Size: 833 bytes --]