Re: [RFC][PATCH 4/7] UBC: syscalls (user interface)
From: Kirill Korotaev
Date: Thu Aug 17 2006 - 08:08:52 EST
Rohit Seth wrote:
On Wed, 2006-08-16 at 20:04 +0100, Alan Cox wrote:
Ar Mer, 2006-08-16 am 11:17 -0700, ysgrifennodd Rohit Seth:
I think there should be a check here for seeing if the new limits are
lower than the current usage of a resource. If so then take appropriate
action.
Generally speaking there isn't a sane appropriate action because the
resources can't just be yanked.
I was more thinking about (for example) user land physical memory limit
for that bean counter. If the limits are going down, then the system
call should try to flush out page cache pages or swap out anonymous
memory. But you are right that it won't be possible in all cases, like
for in kernel memory limits.
Such kind of memory management is less efficient than the one
making decisions based on global shortages and global LRU alogrithm.
The problem here is that doing swap out takes more expensive disk I/O
influencing other users.
So throttling algorithms if wanted should be optional, not mandatory.
Lets postpone it and concentrate on the core.
Thanks,
Kirill
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