Memory reserves or lack thereof

[Konstantin Belousov]

On Mon, Nov 12, 2012 at 05:10:01PM -0600, Alan Cox wrote:
> On 11/12/2012 3:48 PM, Konstantin Belousov wrote:
> > On Mon, Nov 12, 2012 at 01:28:02PM -0800, Sushanth Rai wrote:
> >> This patch still doesn't address the issue of M_NOWAIT calls driving
> >> the memory the all the way down to 2 pages, right ? It would be nice to
> >> have M_NOWAIT just do non-sleep version of M_WAITOK and M_USE_RESERVE
> >> flag to dig deep.
> > This is out of scope of the change. But it is required for any further
> > adjustements.
> 
> I would suggest a somewhat different response:
> 
> The patch does make M_NOWAIT into a "non-sleep version of M_WAITOK" and 
> does reintroduce M_USE_RESERVE as a way to specify "dig deep".
> 
> Currently, both M_NOWAIT and M_WAITOK can drive the cache/free memory 
> down to two pages.  The effect of the patch is to stop M_NOWAIT at two 
> pages rather than allowing it to continue to zero pages.
> 
> When you say, "This is out of scope ...", I believe that you are 
> referring to changing two pages into something larger.  I agree that 
> this is out of scope for the current change.

I referred exactly to the difference between M_USE_RESERVE set or not.
IMO this is what was asked by the question author. So yes, my mean of
the 'out of scope' is about tweaking the 'two pages reserve' in some
way.
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