Awesome: A window manager that gets out of the way

Posted Nov 21, 2011 14:54 UTC (Mon) by nix (subscriber, #2304)
In reply to: Awesome: A window manager that gets out of the way by andresfreund
Parent article: Awesome: A window manager that gets out of the way

That's a very good point. As soon as *anything* exhausts memory, the footprint of *everything* starts to matter... mea culpa, I'd almost forgotten what it was like to run with seriously constrained storage.

Awesome: A window manager that gets out of the way

Posted Nov 21, 2011 15:19 UTC (Mon) by andresfreund (subscriber, #69562) [Link] (1 responses)

Thanks for agreeing ;)

Not sure what youre refering to with constrained storage though. The system I notice this most is a low-end server class/high end workstation hardware...
Even on a RAID10 of 10 rotational disks 4GB/4kb (swapped memory/pagesize) random reads hurt significantly. Especially as in most situations swapin produces loads of synchronous reads.
Calculating it with the worst case load pattern (which is not that unreasonable) and a perfect distribution between devices thats:
>>> (2**30*4/4096)/(7200/60.0*10)
873.8133333333334

seconds. Yuck.

Obviously in reality it won't be quite that bad and the situation can improve considerably if many process are swapping in (because then you suddently don't have only one synchronous request going on at the time) or if you start doing readahead on swap...

Awesome: A window manager that gets out of the way

Posted Nov 21, 2011 22:31 UTC (Mon) by nix (subscriber, #2304) [Link]

The "constrained storage" I meant was "you have run out of memory", really. I was just being excessively general in my terminology...