Smarter write throttling

Smarter write throttling

Posted Oct 2, 2007 11:13 UTC (Tue) by gat3way (guest, #47864)
Parent article: Smarter write throttling

Man, I just wonder how much write I/O you should have on a modern-day system with let's say 2GB of RAM, so that the dirty cache would cause a significant memory pressure? I mean, before pdflush wakes up and writes them back???

On my desktop system with 1 GB RAM, apache server with a PHP application for network monitoring that does lots of mysql INSERTs, 2 testing tomcat5 instances, KDE, evolution and firefox running, according to /proc/meminfo, the memory occupied by dirty pages rarely exceed 10MB...

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This patch is more about servers than desktops.

This is a server with 1700 MB RAM, and it does quite a bit of IO:

# while true; do grep Dirty /proc/meminfo ; sleep 2s ; done
Dirty:          172404 kB
Dirty:          173100 kB
Dirty:          173332 kB
Dirty:          173260 kB
Dirty:          173692 kB
Dirty:          173684 kB
Dirty:          173724 kB
Dirty:          174256 kB
Dirty:          174772 kB
Dirty:          175120 kB
(...)

wouldn't this also be significantly about desktops ?
it seems the grandparent was talking about local disks only, even though article explicitly
mentions other use cases like nfs over gprs :) ).

desktops tend to have all kinds of relatively slow things connected to them - usb drives,
cameras, portable players, all kinds of slow network stuff...
if i understood the idea correctly, these could theoretically block/limit local hdd, which
would otherwise be the fastest device in an average desktop.