On 2 March 2015 at 16:25, Konstantin Belousov <kostik...@gmail.com> wrote:
>> Ok, but is there a specific time length that this should be? > Difference between hold and wire is effectively that held pages are > still kept on the page queues, providing potentially uneccessary work > for pagedaemon to find them and skip. Wired pages are removed from the > queues. > > This means that holding a page is much cheaper, by the cost of leaving > slightly more work to the system. Also, holding a page only requires the > page lock, while wiring contend on the page queue lock, in addition to > the page lock. Thanks for the description - that makes things a lot clearer! >> >> A DMA operation to a slow device could be up to hundreds of >> milliseconds; or seconds if things are really backed up. >> >> Using wire instead of hold definitely made things work without having >> the page disappear from underneath it. Oleksander knows more about the >> details of that. > > Page cannot 'disappear'. The only thing which could happen with the > memory page is reuse, when the page is removed from the previous object > and re-purposed for some other object, loosing old content. > > Your terminology suggests that something unrelated happen. Yup, and that's what I'm worried about :( -adrian _______________________________________________ freebsd-current@freebsd.org mailing list http://lists.freebsd.org/mailman/listinfo/freebsd-current To unsubscribe, send any mail to "freebsd-current-unsubscr...@freebsd.org"
