linux-kernel - Re: [NET]: rt_check_expire() can take a long time, add a cond

lists.openwall.net		lists / announce owl-users owl-dev john-users john-dev passwdqc-users yescrypt popa3d-users / oss-security kernel-hardening musl sabotage tlsify passwords / crypt-dev xvendor / Bugtraq Full-Disclosure linux-kernel linux-netdev linux-ext4 linux-hardening linux-cve-announce PHC
Open Source and information security mailing list archives

Hash Suite: Windows password security audit tool. GUI, reports in PDF.

[<prev] [next>] [<thread-prev] [thread-next>] [day] [month] [year] [list]

Date:	Sat, 17 Nov 2007 23:21:39 +0800
From:	Herbert Xu <herbert@...dor.apana.org.au>
To:	andi@...stfloor.org (Andi Kleen)
Cc:	arjan@...radead.org, dada1@...mosbay.com,
	linux-kernel@...r.kernel.org, davem@...emloft.net,
	netdev@...t.kernel.org, mingo@...e.hu
Subject: Re: [NET]: rt_check_expire() can take a long time, add a cond_resched()

Andi Kleen <andi@...stfloor.org> wrote:
>
>>> > With the extra check (and *much* less function calls), each run
>>> > takes 25ms
> 
> ms?!? The numbers sound wrong. Wrong unit? 

That's quite possible with a huge routing cache.  I think that's
the reason Eric is doing this in the first place.

>> however... this is likely a good argument for making cond_resched() as a
>> whole a #define (or inline) that does this test and then calls the out
>> of line code (which then doesn't need to retest, so it avoids the
>> double test)...
> 
> Disadvantage would be that might_sleep would be commonly skipped then
> (unless you actually need to reschedule) 
> But perhaps that's not a big issue.

On a related note, would it be possible for cond_resched() to
be compiled out completely if we're doing real preemption as
opposed to voluntary preemption?

Cheers,
-- 
Visit Openswan at http://www.openswan.org/
Email: Herbert Xu ~{PmV>HI~} <herbert@...dor.apana.org.au>
Home Page: http://gondor.apana.org.au/~herbert/
PGP Key: http://gondor.apana.org.au/~herbert/pubkey.txt
-
To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
the body of a message to majordomo@...r.kernel.org
More majordomo info at  http://vger.kernel.org/majordomo-info.html
Please read the FAQ at  http://www.tux.org/lkml/