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On i386, double the default size of the bio transient map. With the

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maxbcache size fixed, the auto-tuned transient map is too small for
real-world load on i386.

Tested by:	David Wolfskill
Sponsored by:	The FreeBSD Foundation
This commit is contained in:
kib 2013-03-27 10:56:15 +00:00
parent 2c9ac98d06
commit df3795022f
1 changed files with 13 additions and 6 deletions
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19
sys/kern/vfs_bio.c
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@ -520,6 +520,12 @@ bd_speedup(void)
mtx_unlock(&bdlock);
}
#ifdef __i386__
#define TRANSIENT_DENOM 5
#else
#define TRANSIENT_DENOM 10
#endif
/*
* Calculating buffer cache scaling values and reserve space for buffer
* headers. This is called during low level kernel initialization and
@ -579,8 +585,8 @@ kern_vfs_bio_buffer_alloc(caddr_t v, long physmem_est)
* to the amount of the buffer mapped for typical UFS load.
*
* Clip the buffer map to reserve space for the transient
* BIOs, if its extent is bigger than 90% of the maximum
* buffer map extent on the platform.
* BIOs, if its extent is bigger than 90% (80% on i386) of the
* maximum buffer map extent on the platform.
*
* The fall-back to the maxbuf in case of maxbcache unset,
* allows to not trim the buffer KVA for the architectures
@ -589,7 +595,8 @@ kern_vfs_bio_buffer_alloc(caddr_t v, long physmem_est)
if (bio_transient_maxcnt == 0 && unmapped_buf_allowed) {
maxbuf_sz = maxbcache != 0 ? maxbcache : maxbuf * BKVASIZE;
buf_sz = (long)nbuf * BKVASIZE;
if (buf_sz < maxbuf_sz / 10 * 9) {
if (buf_sz < maxbuf_sz / TRANSIENT_DENOM *
(TRANSIENT_DENOM - 1)) {
/*
* There is more KVA than memory. Do not
* adjust buffer map size, and assign the rest
@ -599,10 +606,10 @@ kern_vfs_bio_buffer_alloc(caddr_t v, long physmem_est)
} else {
/*
* Buffer map spans all KVA we could afford on
* this platform. Give 10% of the buffer map
* to the transient bio map.
* this platform. Give 10% (20% on i386) of
* the buffer map to the transient bio map.
*/
biotmap_sz = buf_sz / 10;
biotmap_sz = buf_sz / TRANSIENT_DENOM;
buf_sz -= biotmap_sz;
}
if (biotmap_sz / INT_MAX > MAXPHYS)