Messages in this thread |  | | | Date | Sat, 18 Oct 2003 14:52:52 +0200 | | From | Jens Axboe <> | | Subject | Re: [PATCH] laptop mode |
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On Fri, Oct 17 2003, Jan Rychter wrote: > >>>>> "Jens" == Jens Axboe <axboe@suse.de> writes: > Jens> On Thu, Oct 09 2003, Marcelo Tosatti wrote: > >> On Thu, 9 Oct 2003, Jeff Garzik wrote: > > Linux Kernel Mailing List wrote: > > > ChangeSet 1.1150.1.52, 2003/10/08 10:49:45-03:00, axboe@suse.de > > > [PATCH] laptop mode > > > > > > Hi Marcelo, > > > > > > Lots of people have been using this patch with great success, > > > and it's been in the SuSE kernel for some months now too. It is > > > also in the -benh ppc tree > > > > > > Basically, it introduces a write back mode of dirty and journal > > > data that is more suitable for laptops. At the block layer end, > > > it schedules write out of dirty data after the disk has been > > > idle for 5 seconds. > > > > > > Laptop mode can be switched on and off with > > > /proc/sys/vm/laptop_mode. There is also a block_dump sysctl, > > > which if enabled will dump who dirties and writes out data. This > > > is very helpful in pinning down who is causing unnecessary > > > writes to the disk. > > > > Red Hat just dropped this patch since it was suspected of data > > corruption ;-( > >> > >> Uh, oh... Jens? > > Jens> See my previous mail. I don't see any problems with it, and I've > Jens> certainly not heard of (or experienced myself) problems with the > Jens> patch. I'm waiting for Jeff to expand on his mail, surely he/RH > Jens> must know more about this issue. > > FWIW, I've been using laptop-mode for a long time now, with no problems > whatsoever. It's a great addition and really helps laptop users.
Glad to hear that.
> On a related note, a very desirable feature would be to be able to trace > which processes do I/O. Unfortunately, Linux distributions aren't very > well adapted to laptops and many applications are way too > "trigger-happy" when it comes to hard drive accesses. I guess most > developers don't use laptops and just assume that they can write or > read data at will. It is very difficult to trace the culprits when your > HD light goes on every couple of seconds.
You do know that the laptop-mode patch included a feature to help with just that very problem, block_dump? If you do
echo "1" > /proc/sys/vm/block_dump (shut down klogd first), it will tell you which process caused the hd activity, either directly or by dirtying a page of data.
-- Jens Axboe
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