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freebsd/sys/geom/geom_io.c
Poul-Henning Kamp f0e185d705 Implement a bio-taskqueue to reduce number of context switches in 
disk I/O processing.

        The intent is that the disk driver in its hardware interrupt
        routine will simply schedule the bio on the task queue with
        a routine to finish off whatever needs done.

        The g_up thread will then schedule this routine, the likely
        outcome of which is a biodone() which queues the bio on
        g_up's regular queue where it will be picked up and processed.

        Compared to the using the regular taskqueue, this saves one
        contextswitch.

Change our scheduling of the g_up and g_down queues to be water-tight,
at the cost of breaking the userland regression test-shims.

Input and ideas from:   scottl
2003-02-11 22:30:26 +00:00

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/*-
* Copyright (c) 2002 Poul-Henning Kamp
* Copyright (c) 2002 Networks Associates Technology, Inc.
* All rights reserved.
*
* This software was developed for the FreeBSD Project by Poul-Henning Kamp
* and NAI Labs, the Security Research Division of Network Associates, Inc.
* under DARPA/SPAWAR contract N66001-01-C-8035 ("CBOSS"), as part of the
* DARPA CHATS research program.
*
* Redistribution and use in source and binary forms, with or without
* modification, are permitted provided that the following conditions
* are met:
* 1. Redistributions of source code must retain the above copyright
* notice, this list of conditions and the following disclaimer.
* 2. Redistributions in binary form must reproduce the above copyright
* notice, this list of conditions and the following disclaimer in the
* documentation and/or other materials provided with the distribution.
* 3. The names of the authors may not be used to endorse or promote
* products derived from this software without specific prior written
* permission.
*
* THIS SOFTWARE IS PROVIDED BY THE AUTHOR AND CONTRIBUTORS ``AS IS'' AND
* ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
* IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
* ARE DISCLAIMED. IN NO EVENT SHALL THE AUTHOR OR CONTRIBUTORS BE LIABLE
* FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
* DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
* OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
* HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
* LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
* OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
* SUCH DAMAGE.
*
* $FreeBSD$
*/
#include <sys/param.h>
#include <sys/stdint.h>
#ifndef _KERNEL
#include <stdio.h>
#include <string.h>
#include <stdlib.h>
#include <signal.h>
#include <err.h>
#include <sched.h>
#else
#include <sys/systm.h>
#include <sys/kernel.h>
#include <sys/malloc.h>
#include <sys/bio.h>
#endif
#include <sys/errno.h>
#include <geom/geom.h>
#include <geom/geom_int.h>
#include <geom/geom_stats.h>
static struct g_bioq g_bio_run_down;
static struct g_bioq g_bio_run_up;
static struct g_bioq g_bio_run_task;
static struct g_bioq g_bio_idle;
static u_int pace;
#include <machine/atomic.h>
static void
g_bioq_lock(struct g_bioq *bq)
{
mtx_lock(&bq->bio_queue_lock);
}
static void
g_bioq_unlock(struct g_bioq *bq)
{
mtx_unlock(&bq->bio_queue_lock);
}
#if 0
static void
g_bioq_destroy(struct g_bioq *bq)
{
mtx_destroy(&bq->bio_queue_lock);
}
#endif
static void
g_bioq_init(struct g_bioq *bq)
{
TAILQ_INIT(&bq->bio_queue);
mtx_init(&bq->bio_queue_lock, "bio queue", NULL, MTX_DEF);
}
static struct bio *
g_bioq_first(struct g_bioq *bq)
{
struct bio *bp;
bp = TAILQ_FIRST(&bq->bio_queue);
if (bp != NULL) {
TAILQ_REMOVE(&bq->bio_queue, bp, bio_queue);
bq->bio_queue_length--;
}
return (bp);
}
static void
g_bioq_enqueue_tail(struct bio *bp, struct g_bioq *rq)
{
g_bioq_lock(rq);
TAILQ_INSERT_TAIL(&rq->bio_queue, bp, bio_queue);
rq->bio_queue_length++;
g_bioq_unlock(rq);
}
struct bio *
g_new_bio(void)
{
struct bio *bp;
g_bioq_lock(&g_bio_idle);
bp = g_bioq_first(&g_bio_idle);
g_bioq_unlock(&g_bio_idle);
if (bp == NULL)
bp = g_malloc(sizeof *bp, M_NOWAIT | M_ZERO);
/* g_trace(G_T_BIO, "g_new_bio() = %p", bp); */
return (bp);
}
void
g_destroy_bio(struct bio *bp)
{
/* g_trace(G_T_BIO, "g_destroy_bio(%p)", bp); */
bzero(bp, sizeof *bp);
g_bioq_enqueue_tail(bp, &g_bio_idle);
}
struct bio *
g_clone_bio(struct bio *bp)
{
struct bio *bp2;
bp2 = g_new_bio();
if (bp2 != NULL) {
bp2->bio_parent = bp;
bp2->bio_cmd = bp->bio_cmd;
bp2->bio_length = bp->bio_length;
bp2->bio_offset = bp->bio_offset;
bp2->bio_data = bp->bio_data;
bp2->bio_attribute = bp->bio_attribute;
bp->bio_children++;
}
/* g_trace(G_T_BIO, "g_clone_bio(%p) = %p", bp, bp2); */
return(bp2);
}
void
g_io_init()
{
g_bioq_init(&g_bio_run_down);
g_bioq_init(&g_bio_run_up);
g_bioq_init(&g_bio_run_task);
g_bioq_init(&g_bio_idle);
}
int
g_io_setattr(const char *attr, struct g_consumer *cp, int len, void *ptr)
{
struct bio *bp;
int error;
g_trace(G_T_BIO, "bio_setattr(%s)", attr);
bp = g_new_bio();
bp->bio_cmd = BIO_SETATTR;
bp->bio_done = NULL;
bp->bio_attribute = attr;
bp->bio_length = len;
bp->bio_data = ptr;
g_io_request(bp, cp);
error = biowait(bp, "gsetattr");
g_destroy_bio(bp);
return (error);
}
int
g_io_getattr(const char *attr, struct g_consumer *cp, int *len, void *ptr)
{
struct bio *bp;
int error;
g_trace(G_T_BIO, "bio_getattr(%s)", attr);
bp = g_new_bio();
bp->bio_cmd = BIO_GETATTR;
bp->bio_done = NULL;
bp->bio_attribute = attr;
bp->bio_length = *len;
bp->bio_data = ptr;
g_io_request(bp, cp);
error = biowait(bp, "ggetattr");
*len = bp->bio_completed;
g_destroy_bio(bp);
return (error);
}
static int
g_io_check(struct bio *bp)
{
struct g_consumer *cp;
struct g_provider *pp;
cp = bp->bio_from;
pp = bp->bio_to;
/* Fail if access counters dont allow the operation */
switch(bp->bio_cmd) {
case BIO_READ:
case BIO_GETATTR:
if (cp->acr == 0)
return (EPERM);
break;
case BIO_WRITE:
case BIO_DELETE:
case BIO_SETATTR:
if (cp->acw == 0)
return (EPERM);
break;
default:
return (EPERM);
}
/* if provider is marked for error, don't disturb. */
if (pp->error)
return (pp->error);
switch(bp->bio_cmd) {
case BIO_READ:
case BIO_WRITE:
case BIO_DELETE:
/* Reject I/O not on sector boundary */
if (bp->bio_offset % pp->sectorsize)
return (EINVAL);
/* Reject I/O not integral sector long */
if (bp->bio_length % pp->sectorsize)
return (EINVAL);
/* Reject requests past the end of media. */
if (bp->bio_offset > pp->mediasize)
return (EIO);
break;
default:
break;
}
return (0);
}
void
g_io_request(struct bio *bp, struct g_consumer *cp)
{
struct g_provider *pp;
struct bintime bt;
pp = cp->provider;
KASSERT(cp != NULL, ("NULL cp in g_io_request"));
KASSERT(bp != NULL, ("NULL bp in g_io_request"));
KASSERT(bp->bio_data != NULL, ("NULL bp->data in g_io_request"));
KASSERT(pp != NULL, ("consumer not attached in g_io_request"));
bp->bio_from = cp;
bp->bio_to = pp;
bp->bio_error = 0;
bp->bio_completed = 0;
if (g_collectstats) {
binuptime(&bt);
bp->bio_t0 = bt;
if (cp->stat->nop == cp->stat->nend)
cp->stat->wentbusy = bt; /* Consumer is idle */
if (pp->stat->nop == pp->stat->nend)
pp->stat->wentbusy = bt; /* Provider is idle */
}
cp->stat->nop++;
pp->stat->nop++;
/* Pass it on down. */
g_trace(G_T_BIO, "bio_request(%p) from %p(%s) to %p(%s) cmd %d",
bp, cp, cp->geom->name, pp, pp->name, bp->bio_cmd);
g_bioq_enqueue_tail(bp, &g_bio_run_down);
wakeup(&g_wait_down);
}
void
g_io_deliver(struct bio *bp, int error)
{
struct g_consumer *cp;
struct g_provider *pp;
struct bintime t1, dt;
int idx;
cp = bp->bio_from;
pp = bp->bio_to;
KASSERT(bp != NULL, ("NULL bp in g_io_deliver"));
KASSERT(cp != NULL, ("NULL bio_from in g_io_deliver"));
KASSERT(cp->geom != NULL, ("NULL bio_from->geom in g_io_deliver"));
KASSERT(pp != NULL, ("NULL bio_to in g_io_deliver"));
g_trace(G_T_BIO,
"g_io_deliver(%p) from %p(%s) to %p(%s) cmd %d error %d off %jd len %jd",
bp, cp, cp->geom->name, pp, pp->name, bp->bio_cmd, error,
(intmax_t)bp->bio_offset, (intmax_t)bp->bio_length);
if (g_collectstats) {
switch (bp->bio_cmd) {
case BIO_READ: idx = G_STAT_IDX_READ; break;
case BIO_WRITE: idx = G_STAT_IDX_WRITE; break;
case BIO_DELETE: idx = G_STAT_IDX_DELETE; break;
case BIO_GETATTR: idx = -1; break;
case BIO_SETATTR: idx = -1; break;
default:
panic("unknown bio_cmd in g_io_deliver");
break;
}
binuptime(&t1);
/* Raise the "inconsistent" flag for userland */
atomic_add_acq_int(&cp->stat->seq0, 1);
atomic_add_acq_int(&pp->stat->seq0, 1);
if (idx >= 0) {
/* Account the service time */
dt = t1;
bintime_sub(&dt, &bp->bio_t0);
bintime_add(&cp->stat->ops[idx].dt, &dt);
bintime_add(&pp->stat->ops[idx].dt, &dt);
/* ... and the metrics */
pp->stat->ops[idx].nbyte += bp->bio_completed;
cp->stat->ops[idx].nbyte += bp->bio_completed;
pp->stat->ops[idx].nop++;
cp->stat->ops[idx].nop++;
/* ... and any errors */
if (error == ENOMEM) {
cp->stat->ops[idx].nmem++;
pp->stat->ops[idx].nmem++;
} else if (error != 0) {
cp->stat->ops[idx].nerr++;
pp->stat->ops[idx].nerr++;
}
}
/* Account for busy time on the consumer */
dt = t1;
bintime_sub(&dt, &cp->stat->wentbusy);
bintime_add(&cp->stat->bt, &dt);
cp->stat->wentbusy = t1;
/* Account for busy time on the provider */
dt = t1;
bintime_sub(&dt, &pp->stat->wentbusy);
bintime_add(&pp->stat->bt, &dt);
pp->stat->wentbusy = t1;
/* Mark the structures as consistent again */
atomic_add_acq_int(&cp->stat->seq1, 1);
atomic_add_acq_int(&pp->stat->seq1, 1);
}
cp->stat->nend++;
pp->stat->nend++;
if (error == ENOMEM) {
printf("ENOMEM %p on %p(%s)\n", bp, pp, pp->name);
g_io_request(bp, cp);
pace++;
return;
}
bp->bio_error = error;
g_bioq_enqueue_tail(bp, &g_bio_run_up);
wakeup(&g_wait_up);
}
void
g_io_schedule_down(struct thread *tp __unused)
{
struct bio *bp;
off_t excess;
int error;
struct mtx mymutex;
bzero(&mymutex, sizeof mymutex);
mtx_init(&mymutex, "g_xdown", MTX_DEF, 0);
for(;;) {
g_bioq_lock(&g_bio_run_down);
bp = g_bioq_first(&g_bio_run_down);
if (bp == NULL) {
msleep(&g_wait_down, &g_bio_run_down.bio_queue_lock,
PRIBIO | PDROP, "g_down", hz/10);
continue;
}
g_bioq_unlock(&g_bio_run_down);
error = g_io_check(bp);
if (error) {
g_io_deliver(bp, error);
continue;
}
switch (bp->bio_cmd) {
case BIO_READ:
case BIO_WRITE:
case BIO_DELETE:
/* Truncate requests to the end of providers media. */
excess = bp->bio_offset + bp->bio_length;
if (excess > bp->bio_to->mediasize) {
excess -= bp->bio_to->mediasize;
bp->bio_length -= excess;
}
/* Deliver zero length transfers right here. */
if (bp->bio_length == 0) {
g_io_deliver(bp, 0);
continue;
}
break;
default:
break;
}
mtx_lock(&mymutex);
bp->bio_to->geom->start(bp);
mtx_unlock(&mymutex);
if (pace) {
pace--;
break;
}
}
}
void
bio_taskqueue(struct bio *bp, bio_task_t *func, void *arg)
{
bp->bio_task = func;
bp->bio_task_arg = arg;
/*
* The taskqueue is actually just a second queue off the "up"
* queue, so we use the same lock.
*/
g_bioq_lock(&g_bio_run_up);
TAILQ_INSERT_TAIL(&g_bio_run_task.bio_queue, bp, bio_queue);
g_bio_run_task.bio_queue_length++;
wakeup(&g_wait_up);
g_bioq_unlock(&g_bio_run_up);
}
void
g_io_schedule_up(struct thread *tp __unused)
{
struct bio *bp;
struct mtx mymutex;
bzero(&mymutex, sizeof mymutex);
mtx_init(&mymutex, "g_xup", MTX_DEF, 0);
for(;;) {
g_bioq_lock(&g_bio_run_up);
bp = g_bioq_first(&g_bio_run_task);
if (bp != NULL) {
g_bioq_unlock(&g_bio_run_up);
mtx_lock(&mymutex);
bp->bio_task(bp, bp->bio_task_arg);
mtx_unlock(&mymutex);
continue;
}
bp = g_bioq_first(&g_bio_run_up);
if (bp != NULL) {
g_bioq_unlock(&g_bio_run_up);
mtx_lock(&mymutex);
biodone(bp);
mtx_unlock(&mymutex);
continue;
}
msleep(&g_wait_up, &g_bio_run_up.bio_queue_lock,
PRIBIO | PDROP, "g_up", hz/10);
}
}
void *
g_read_data(struct g_consumer *cp, off_t offset, off_t length, int *error)
{
struct bio *bp;
void *ptr;
int errorc;
bp = g_new_bio();
bp->bio_cmd = BIO_READ;
bp->bio_done = NULL;
bp->bio_offset = offset;
bp->bio_length = length;
ptr = g_malloc(length, 0);
bp->bio_data = ptr;
g_io_request(bp, cp);
errorc = biowait(bp, "gread");
if (error != NULL)
*error = errorc;
g_destroy_bio(bp);
if (errorc) {
g_free(ptr);
ptr = NULL;
}
return (ptr);
}
int
g_write_data(struct g_consumer *cp, off_t offset, void *ptr, off_t length)
{
struct bio *bp;
int error;
bp = g_new_bio();
bp->bio_cmd = BIO_WRITE;
bp->bio_done = NULL;
bp->bio_offset = offset;
bp->bio_length = length;
bp->bio_data = ptr;
g_io_request(bp, cp);
error = biowait(bp, "gwrite");
g_destroy_bio(bp);
return (error);
}
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