N900, ohmd, syspart, VM & swap tweaks - Page 3 - maemo.org

Tigerite | # 21 | 2011-05-31, 14:24 | Report

Has anyone ever tried the deadline scheduler and:

Code:

echo 1 > /sys/block/mmcblkX/queue/iosched/fifo_batch

? I've just compiled BFS with the config option enabled, and will be giving it a try over the next few days. I got the idea from here

hawaii | # 22 | 2011-06-01, 04:01 | Report

I'd also like to try the anticipatory scheduler, a lot of the Android guys have been switching over to it...

Last edited by hawaii; 2011-06-01 at 04:04.

Tigerite | # 23 | 2011-06-01, 08:33 | Report

I considered anticipatory, but it was taken out of the kernel altogether as of 2.6.33 and supposedly CFQ replaced it after 2.6.18. Also I'm never sure whether heuristics are a good idea or not.. I suppose it wouldn't hurt to add it to the config as a module, though.

Tigerite | # 24 | 2011-06-01, 11:04 | Report

Ok, I've built the latest BFS from git tree, with both deadline and anticipatory enabled as modules within the config. Everything runs as smoothly as before, with no added overhead. To enable either one of them, you have to echo deadline or anticipatory to /sys/block/mmcblk0/queue/scheduler - this seems to automagically insert the corresponding module (probably best to rmmod if you then change back to noop or cfq at a later date, though, as they stay loaded). I did find a thread regarding anticipatory on Android and found this snippet to be quite interesting:

Originally Posted by

For instance anticipatory scheduler focuses on contiunous read and avoiding head movement which is not the case for flash drives.

Completely different rules apply here.

The community (Linux SSD) recommends NOOP or DEADLINE schedulers, I prefered DEADLINE for it's focus on preventing read starvation.
It works the best (elevator = deadline) for my Asus EEE PC 901 with SSD drives and attached SD cards.
Writes are slower, but there's much less lag when browsing web or opening folders because "read" operations have priority.
The same seems to work on my Galaxy S with stock JM1 with or without one-click-lag-fix.

..which makes me think deadline might be the best scheduler to use, even though the N900's drive isn't exactly an SSD?

Last edited by Tigerite; 2011-06-01 at 11:06.

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MONVMENTVM | # 25 | 2011-06-01, 18:16 | Report

Originally Posted by Tigerite View Post

Ok, I've built the latest BFS from git tree, with both deadline and anticipatory enabled as modules within the config. Everything runs as smoothly as before, with no added overhead. To enable either one of them, you have to echo deadline or anticipatory to /sys/block/mmcblk0/queue/scheduler - this seems to automagically insert the corresponding module (probably best to rmmod if you then change back to noop or cfq at a later date, though, as they stay loaded). I did find a thread regarding anticipatory on Android and found this snippet to be quite interesting:

..which makes me think deadline might be the best scheduler to use, even though the N900's drive isn't exactly an SSD?

Probably because most processes hang on read operations. Giving them higher priority should speed things up for normal usage. So I think when you're downloading something and at the same time are trying to start an app etc. the device should be snappier, while you couldn't care less about the download.

joerg_rw | # 26 | 2011-06-19, 22:53 | Report

Originally Posted by vi_ View Post

Holy WALL OF TEXT bro. Please, some formatting!

HOLY, and you fullquote it, to add that one liner comment :-S
/j

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F2thaK | # 27 | 2011-06-19, 23:46 | Report

Originally Posted by jurop88 View Post

Everything said, here follows a resume of my experiences so far.
...

Thanks, just applied all your settings. See how things go.

pigeond | # 28 | 2012-03-14, 02:03 | Report

Hi all,

I've also been trying to tweak /usr/share/policy/etc/current/syspart.conf

One thing I noticed though is, sometimes the values are being applied for a little while, and then it gets overridden again by ohmd.

For example, I've tried changing the desktop cpu-shares to say 4096, then i run "stop ohmd" and "start ohmd". For a short time, I can see the value 4096 is being set by cat-ing the corresponding value in /syspart/desktop/cpu.shares

But then after a while, ohmd seems to write back the original value 6144 to it.

Any ideas?

Thanks.

Last edited by pigeond; 2012-03-14 at 02:11.

jurop88 | # 29 | 2012-03-14, 07:21 | Report

Now I don't remember exactly - I worked on that a long ago - but there is a policy file written and compiled in Prolog (?) somewhere read by ohmd - and it's responsible for that.
Long story short, what I remember is that I resigned after a lot of searching. Now I am really short on time for next month, but if you are interested in looking at that I can look for my knowledge and send everything to you - some material found on wikis, irc logs and the like

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freemangordon | # 30 | 2012-03-14, 08:02 | Report

Originally Posted by jurop88 View Post

Now I don't remember exactly - I worked on that a long ago - but there is a policy file written and compiled in Prolog (?) somewhere read by ohmd - and it's responsible for that.
Long story short, what I remember is that I resigned after a lot of searching. Now I am really short on time for next month, but if you are interested in looking at that I can look for my knowledge and send everything to you - some material found on wikis, irc logs and the like

...or even better send it to some of the CSSU developers/maintainers (me, Pali, merlin1991,...)

Thanks.

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