linux-kernel - Re: [PATCH] x86: Change x86 to use generic find_next

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]

Message-ID: <87zlt7zlov.fsf@basil.nowhere.org>
Date:	09 Mar 2008 21:28:32 +0100
From:	Andi Kleen <andi@...stfloor.org>
To:	Alexander van Heukelum <heukelum@...lshack.com>
Cc:	Thomas Gleixner <tglx@...utronix.de>, Ingo Molnar <mingo@...e.hu>,
	"H. Peter Anvin" <hpa@...or.com>,
	LKML <linux-kernel@...r.kernel.org>, heukelum@...tmail.fm
Subject: Re: [PATCH] x86: Change x86 to use generic find_next_bit

Alexander van Heukelum <heukelum@...lshack.com> writes:
> 
> If the bitmap size is not a multiple of BITS_PER_LONG, and no set 
> (cleared) bit is found, find_next_bit (find_next_zero_bit) returns a 
> value outside of the range [0,size]. The generic version always returns 
> exactly size.

With that change it is likely possible to remove the min(NR_CPUS in
lib/cpumask.c __first/__next_cpu. iirc it was just a workaround for
the x86 quirk. I suspect with such a change it would be possible to
inline those again, possibly speeding up some loops who do cpumask
walking (iirc the scheduler used to do that frequently)

-Andi

--
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/