Re: how to recycle Inact memory more aggressively?

On 13 March 2016 at 18:51, Mark Johnston <markj_at_freebsd.org> wrote:
> On Sun, Mar 13, 2016 at 06:33:46PM -0700, Adrian Chadd wrote:
>> Hi,
>>
>> I can reproduce this by doing a mkimage on a large destination file
>> image. it looks like it causes all the desktop processes to get paged
>> out whilst it's doing so, and then the whole UI freezes until it
>> catches up.
>
> mkimg(1) maps the destination file with MAP_NOSYNC, so if it's larger
> than RAM, I think it'll basically force the pagedaemon to write out the
> image as it tries to reclaim pages from the inactive queue. This can
> cause stalls if the pagedaemon blocks waiting for some I/O to complete.
> The user/alc/PQ_LAUNDRY branch helps alleviate this problem by using a
> different thread to launder dirty pages. I use mkimg on various desktop
> machines to build bhyve images and have noticed the problem you're
> describing; PQ_LAUNDRY helps quite a bit in that case. But I don't know
> why this would be a new problem.
>

That's why I'm confused. I just know that it didn't used to cause the
whole UI to hang due to paging.



-adrian