tmpfs use of wired_count
jeseems at gmail.com
Wed Jun 30 17:03:01 UTC 2010
I am a newbie on freebsd kernel. Am currently trying to debug a scenario,
where a custom driver I load uses a lot of static memory and hence lots of
The system still has a lot of free memory ( more than 200MB) and a free swap
space ( > 500MB).
Once I load the driver, the tmpfs loaded on /tmp shows a size of 0.
in tmpfs/tmpfs.h, I see that the free memory available is reduced by number
of wired pages ( see code below).
Is this correct logic ? why do we need to reduce wired count from free
pages available ?
* Returns information about the number of available memory pages,
* including physical and virtual ones.
* If 'total' is TRUE, the value returned is the total amount of memory
* pages configured for the system (either in use or free).
* If it is FALSE, the value returned is the amount of free memory pages.
* Remember to remove TMPFS_PAGES_RESERVED from the returned value to avoid
* excessive memory usage.
static __inline size_t
size = swap_pager_avail + cnt.v_free_count + cnt.v_inactive_count;
size -= size > cnt.v_wire_count ? cnt.v_wire_count : size;
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