Re: Best OS & Configuration for Dual Xeon w/4GB & Adaptec RAID 2200S

Поиск
Список
Период
Сортировка
От Jim C. Nasby
Тема Re: Best OS & Configuration for Dual Xeon w/4GB & Adaptec RAID 2200S
Дата
Msg-id 20060321103219.GD15742@pervasive.com
обсуждение исходный текст
Ответ на Re: Best OS & Configuration for Dual Xeon w/4GB & Adaptec RAID 2200S  (Vivek Khera <vivek@khera.org>)
Ответы Re: Best OS & Configuration for Dual Xeon w/4GB & Adaptec  (Mark Kirkwood <markir@paradise.net.nz>)
Список pgsql-performance
On Mon, Mar 20, 2006 at 02:15:22PM -0500, Vivek Khera wrote:
> I think FreeBSD has a hard upper limit on the total ram it will use
> for disk cache.  I haven't been able to get reliable, irrefutable,
> answers about it, though.

It does not. Any memory in the inactive queue is effectively your 'disk
cache'. Pages start out in the active queue, and if they aren't used
fairly frequently they will move into the inactive queue. From there
they will be moved to the cache queue, but only if the cache queue falls
below a certain threshold, because in order to go into the cache queue
the page must be marked clean, possibly incurring a write to disk. AFAIK
pages only go into the free queue if they have been completely released
by all objects that were referencing them, so it's theoretically
posisble for that queue to go to 0.
--
Jim C. Nasby, Sr. Engineering Consultant      jnasby@pervasive.com
Pervasive Software      http://pervasive.com    work: 512-231-6117
vcard: http://jim.nasby.net/pervasive.vcf       cell: 512-569-9461

В списке pgsql-performance по дате отправления:

Предыдущее
От: "Jim C. Nasby"
Дата:
Сообщение: Re: Best OS & Configuration for Dual Xeon w/4GB &
Следующее
От: Mark Kirkwood
Дата:
Сообщение: Re: planner with index scan cost way off actual cost,