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Add disk I/O scheduling for positively niced processes.

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When a positively niced process requests a disk I/O, make
it wait for its nice value of ticks before scheduling its
I/O request if there are any other processes with I/O
requests in the disk queue. For all the gory details, see
the ``Running fsck in the Background'' paper in the Usenix
BSDCon 2002 Conference Proceedings, pages 55-64.
This commit is contained in:
Kirk McKusick 2001-12-14 05:50:44 +00:00
parent 05463bb58d
commit d8bddaa85d
1 changed files with 25 additions and 0 deletions
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25
sys/kern/subr_disklabel.c
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@ -44,11 +44,24 @@
#include <sys/bio.h>
#include <sys/buf.h>
#include <sys/conf.h>
#include <sys/kernel.h>
#include <sys/disklabel.h>
#include <sys/diskslice.h>
#include <sys/syslog.h>
#include <machine/atomic.h>
/*
* Mutex to use when delaying niced I/O bound processes in bioqdisksort().
*/
static struct mtx dksort_mtx;
static void
dksort_init(void)
{
mtx_init(&dksort_mtx, "dksort", MTX_DEF);
}
SYSINIT(dksort, SI_SUB_DRIVERS, SI_ORDER_MIDDLE, dksort_init, NULL)
/*
* Seek sort for disks.
*
@ -72,7 +85,19 @@ bioqdisksort(bioq, bp)
struct bio *bq;
struct bio *bn;
struct bio *be;
struct thread *td = curthread;
if (td && td->td_ksegrp->kg_nice > 0) {
TAILQ_FOREACH(bn, &bioq->queue, bio_queue)
if (BIOTOBUF(bn)->b_vp != BIOTOBUF(bn)->b_vp)
break;
if (bn != NULL) {
mtx_lock(&dksort_mtx);
msleep((caddr_t)&dksort_mtx, &dksort_mtx,
PPAUSE | PCATCH | PDROP, "ioslow",
td->td_ksegrp->kg_nice);
}
}
if (!atomic_cmpset_int(&bioq->busy, 0, 1))
panic("Recursing in bioqdisksort()");
be = TAILQ_LAST(&bioq->queue, bio_queue);