From owner-cvs-all Sun Nov 25 19:50:32 2001 Delivered-To: cvs-all@freebsd.org Received: from obsecurity.dyndns.org (adsl-64-165-226-105.dsl.lsan03.pacbell.net [64.165.226.105]) by hub.freebsd.org (Postfix) with ESMTP id 07D4A37B41A; Sun, 25 Nov 2001 19:50:23 -0800 (PST) Received: by obsecurity.dyndns.org (Postfix, from userid 1000) id 5563366BE2; Sun, 25 Nov 2001 19:50:22 -0800 (PST) Date: Sun, 25 Nov 2001 19:50:22 -0800 From: Kris Kennaway To: Sean Chittenden Cc: Ian Dowse , Kris Kennaway , cvs-committers@FreeBSD.org, cvs-all@FreeBSD.org Subject: Re: cvs commit: src/usr.bin/tail forward.c Message-ID: <20011125195022.A8376@xor.obsecurity.org> References: <20011125153656.A94203@xor.obsecurity.org> <200111260038.aa52845@salmon.maths.tcd.ie> <2001@=> <20011125193957.O20895@ninja1.internal> Mime-Version: 1.0 Content-Type: multipart/signed; micalg=pgp-md5; protocol="application/pgp-signature"; boundary="zYM0uCDKw75PZbzx" Content-Disposition: inline User-Agent: Mutt/1.2.5i In-Reply-To: <20011125193957.O20895@ninja1.internal>; from sean@chittenden.org on Sun, Nov 25, 2001 at 07:39:57PM -0800 Sender: owner-cvs-all@FreeBSD.ORG Precedence: bulk List-ID: List-Archive: (Web Archive) List-Help: (List Instructions) List-Subscribe: List-Unsubscribe: X-Loop: FreeBSD.ORG --zYM0uCDKw75PZbzx Content-Type: text/plain; charset=us-ascii Content-Disposition: inline Content-Transfer-Encoding: quoted-printable On Sun, Nov 25, 2001 at 07:39:57PM -0800, Sean Chittenden wrote: > > >I dunno..the major use of tail -F is probably on logfiles which get > > >rotated infrequently. I can imagine that a site might want to > > >simultaneously monitor a large number of logfiles, but I don't know > > >what the CPU impact of that with your change would be..maybe not much. > > >If you tail -F, say, 100 simultaneous files, how much CPU does that > > >stat'ing use? > >=20 > > Running 100 "tail -F"s requires a pretty negliglible amount of CPU > > time (try it!), but kqueue does help by allowing the processes to > > be swapped out during any long pauses between file updates. > >=20 > > The reason for this change is simply to fix a particular use of > > tail that was broken by the addition of kqueue support. The current > > code gives us about half of the kqueue gains over the pre-kqueue > > version for the -F case (changes noticed quickly, polling frequency > > reduced by a factor of 4). Doing better is of course possible, but > > it doesn't seem particularly easy. Maybe the author of this patch > > (Maxim Konovalov) would be willing to have a go at it. >=20 > Why not wrap this functionality in a new CLI argument? If I'm tailing > over NFS or some non-kq enabled FS, then I'll turn on the flag > manually (ex: -N). Seems like this is a step backwards to me... -sc No, you're misunderstanding the nature of the change. Kris --zYM0uCDKw75PZbzx Content-Type: application/pgp-signature Content-Disposition: inline -----BEGIN PGP SIGNATURE----- Version: GnuPG v1.0.6 (FreeBSD) Comment: For info see http://www.gnupg.org iD8DBQE8Abv8Wry0BWjoQKURAplSAJ4ixwCijMiLDAvwJ3o9kweMljK/SgCfXGI2 6U2E3eNoiCt5QOGBoDMInSA= =nXaD -----END PGP SIGNATURE----- --zYM0uCDKw75PZbzx-- To Unsubscribe: send mail to majordomo@FreeBSD.org with "unsubscribe cvs-all" in the body of the message