Memory reserves or lack thereof

[Sushanth Rai]

--- On Mon, 11/12/12, Alan Cox <alc at rice.edu> wrote:

> From: Alan Cox <alc at rice.edu>
> Subject: Re: Memory reserves or lack thereof
> To: "Konstantin Belousov" <kostikbel at gmail.com>
> Cc: "Sushanth Rai" <sushanth_rai at yahoo.com>, alc at freebsd.org, pho at freebsd.org, "StevenSears" <Steven.Sears at netapp.com>, "freebsd-hackers at freebsd.org" <freebsd-hackers at freebsd.org>
> Date: Monday, November 12, 2012, 3:10 PM
> 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.


Thanks for the correction. I was associating VM_ALLOC_SYSTEM with just M_NOWAIT as it seemed in the first verion of the patch.

Sushanth