Hi Andrew,
On 04/05/2013 11:02 PM, Andrew Shewmaker wrote:
On Wed, Apr 3, 2013 at 9:50 PM, Simon Jeons <simon.jeons@xxxxxxxxx> wrote:
FAQ
...
* How do you calculate a minimum useful reserve?
A user or the admin needs enough memory to login and perform
recovery operations, which includes, at a minimum:
sshd or login + bash (or some other shell) + top (or ps, kill, etc.)
For overcommit 'guess', we can sum resident set sizes (RSS).
On x86_64 this is about 8MB.
For overcommit 'never', we can take the max of their virtual sizes
(VSZ)
and add the sum of their RSS.
On x86_64 this is about 128MB.
1.Why has this different between guess and never?
The default, overcommit 'guess' mode, only needs a reserve for
what the recovery programs will typically use. Overcommit 'never'
mode will only successfully launch an app when it can fulfill all of
its requested memory allocations--even if the app only uses a
fraction of what it asks for.
VSZ has already cover RSS, is it? why account RSS again?
2.You just test x86/x86_64, other platforms also will use memory overcommit,
did you test them?
No, I haven't. Unfortunately, I don't currently have any other platforms to test
with. I'll see what I can do.
Thanks,
Andrew
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