Date: Tue, 5 May 2009 19:19:14 +1000 From: Peter Jeremy <peterjeremy@optushome.com.au> To: Alexander Motin <mav@freebsd.org> Cc: FreeBSD acpi <freebsd-acpi@freebsd.org>, FreeBSD-Current <freebsd-current@freebsd.org>, freebsd-mobile@freebsd.org Subject: Re: Fighting for the power. Message-ID: <20090505091914.GA94521@server.vk2pj.dyndns.org> In-Reply-To: <49FE5EC8.3040205@FreeBSD.org> References: <49FE1826.4060000@FreeBSD.org> <49FE29A4.30507@root.org> <49FE5EC8.3040205@FreeBSD.org>
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--cWoXeonUoKmBZSoM Content-Type: text/plain; charset=us-ascii Content-Disposition: inline Content-Transfer-Encoding: quoted-printable On 2009-May-04 06:19:36 +0300, Alexander Motin <mav@freebsd.org> wrote: >System will always have tons of waiting callouts and timeouts to be=20 >handled. So timer will be always needed. Working timer. Yes, but a tickless kernel will let the CPU stay asleep for longer since it doesn't need to wake up just to discover there's nothing to do. >number of idle disk write activity, but I haven't very succeeded. Even=20 >in my quite simple icewm X environment something was persistently=20 >writing something every several minutes. I have found and disabled some=20 >activity sources, but it was not enough. I've recently (in the last few days) worked through minimising the write activity on the SSD in my laptop (I wrote a tool that monitors write transfers via devstat(3) and it would be possible to track down the actual modified files via kqueue(2) if necessary). I'm now down to about two chunks of about 13 transfers each per hour (due to entopy saving and ntp.drift updating). The changes I made were: 1) Mount the SSD filesystems as noatime 2) Turn off all local syslogging (syslog is directed to another system when my laptop is at home, lost otherwise). 3) Change maillog rotation to size instead of daily 4) Run save-entropy once per hour instead of every 11 minutes. 5) Patch the save-entropy script to reduce the write load when it's run (see PR bin/134225). 6) Use a swap-back /tmp By default, ntpd updates ntp.drift every hour. I might do some monitoring and see if the drift changes significantly over time. If it doesn't, hard-wiring the ntp.drift file will save some writes. (The other option would be to tweak the relevant timecounter until the actual drift is 0 and then stop ntpd and just run something like ntpdate regularly to compensate for the remaining drift). Experimentation shows that firefox3 generates a fairly heavy write load - continuously updating several internal databases whilst it is in use. Turning off the "Block reported attack sites" and "Block reported web forgeries" options under 'Security' stops it updating urlclassifier3.sqlite. Note that when you update a file, you implicitly update the associated inode and the filesystem superbock. > What would happen in some=20 >complicated KDE/Gnome environment I am just afraid to think. I'd recommend avoiding a heavyweight window manager and using something like fwvm or vtwm. --=20 Peter Jeremy --cWoXeonUoKmBZSoM Content-Type: application/pgp-signature Content-Disposition: inline -----BEGIN PGP SIGNATURE----- Version: GnuPG v2.0.11 (FreeBSD) iEYEARECAAYFAkoABJIACgkQ/opHv/APuIfq8wCdH8DXPq3Vv0V1hzLBO1KOmnG8 67AAnjuB8SS3/vaNaSu5WP+7b7xHQ6Xj =ZLjp -----END PGP SIGNATURE----- --cWoXeonUoKmBZSoM--
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