Avoid requeuing active pages in vm_swapout_object_deactivate_pages().

[markj]

Summary

Elsewhere (e.g., vm_page_unwire()) we avoid requeuing active pages, so
there is not much sense in doing it here.

[dougm]

Seems plausible.

[kib]

I think that requeues there do help fairness, since we call pmap_ts_referenced() and check for PGA_REFERENCED. If we bumped act_count, then it is prudent to handle the page similar to the pagedaemon. OTOH, I do not object to the change.

[markj]

In D21343#464279, @kib wrote:

I think that requeues there do help fairness, since we call pmap_ts_referenced() and check for PGA_REFERENCED. If we bumped act_count, then it is prudent to handle the page similar to the pagedaemon. OTOH, I do not object to the change.

The page daemon does not requeue pages after bumping act_count, though. This was changed in r332974.

[markj]

In D21343#464293, @markj wrote:

In D21343#464279, @kib wrote:

I think that requeues there do help fairness, since we call pmap_ts_referenced() and check for PGA_REFERENCED. If we bumped act_count, then it is prudent to handle the page similar to the pagedaemon. OTOH, I do not object to the change.

The page daemon does not requeue pages after bumping act_count, though. This was changed in r332974.

I should add that the above statement is only true for pages in PQ_ACTIVE, which is the case for pages affected by this diff. For pages in PQ_INACTIVE or PQ_LAUNDRY, if the backing object is unmapped (i.e. object->ref_count == 0), we will requeue the page upon discovering a reference.

[kib]

In D21343#464293, @markj wrote:

In D21343#464279, @kib wrote:

I think that requeues there do help fairness, since we call pmap_ts_referenced() and check for PGA_REFERENCED. If we bumped act_count, then it is prudent to handle the page similar to the pagedaemon. OTOH, I do not object to the change.

The page daemon does not requeue pages after bumping act_count, though. This was changed in r332974.

May be add the first sentence from this response as a comment in place of removed requeues.