linux-kernel - Re: all syscalls initially taking 4usec on a P4? Re: nonblocking UDPv4 recvfrom() taking 4usec @ 3GHz?

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: <20070220194040.GA18976@kvack.org>
Date:	Tue, 20 Feb 2007 14:40:40 -0500
From:	Benjamin LaHaise <bcrl@...ck.org>
To:	bert hubert <bert.hubert@...herlabs.nl>,
	Evgeniy Polyakov <johnpol@....mipt.ru>,
	Josef Sipek <jsipek@....cs.sunysb.edu>,
	Andi Kleen <andi@...stfloor.org>, netdev@...r.kernel.org,
	linux-kernel@...r.kernel.org
Subject: Re: all syscalls initially taking 4usec on a P4? Re: nonblocking UDPv4 recvfrom() taking 4usec @ 3GHz?

On Tue, Feb 20, 2007 at 08:33:20PM +0100, bert hubert wrote:
> I'm investigating this further for other system calls. It might be that my
> measurements are off, but it appears even a slight delay between calls
> incurs a large penalty.

Make sure your system is idle.  Userspace bloat means that *lots* of idle 
activity occurs in between timer ticks on recent distributions -- all those 
widgets polling the hardware to see if something changed or needs updating 
do a lot of damage to the caches.  Try comparing a run under init=/bin/bash 
with one while logged in to a desktop environment to see just how painful it 
is.

		-ben
-- 
"Time is of no importance, Mr. President, only life is important."
Don't Email: <dont@...ck.org>.
-
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/