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Re: [Qemu-devel] [PATCH v3] fsdev: add IO throttle support to fsdev devi
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From: |
Greg Kurz |
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Subject: |
Re: [Qemu-devel] [PATCH v3] fsdev: add IO throttle support to fsdev devices |
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Date: |
Wed, 21 Sep 2016 00:15:00 +0200 |
On Fri, 16 Sep 2016 04:33:36 -0400
Pradeep Jagadeesh <address@hidden> wrote:
> Uses throttling APIs to limit I/O bandwidth and number of operations on the
> fsdev devices.
>
> Signed-off-by: Pradeep Jagadeesh <address@hidden>
> ---
Hi Pradeep,
Please find some comments below.
> fsdev/Makefile.objs | 1 +
> fsdev/file-op-9p.h | 3 +
> fsdev/qemu-fsdev-opts.c | 76 ++++++++++++++++++
> fsdev/qemu-fsdev-throttle.c | 191
> ++++++++++++++++++++++++++++++++++++++++++++
> fsdev/qemu-fsdev-throttle.h | 42 ++++++++++
Is the qemu- prefix really needed ?
> hw/9pfs/9p-local.c | 11 ++-
> hw/9pfs/9p.c | 7 ++
> hw/9pfs/cofile.c | 3 +
> 8 files changed, 332 insertions(+), 2 deletions(-)
> create mode 100644 fsdev/qemu-fsdev-throttle.c
> create mode 100644 fsdev/qemu-fsdev-throttle.h
>
> This adds the support for the 9p-local driver.
> For now this functionality can be enabled only through qemu cli options.
> QMP interface and support to other drivers need further extensions.
> To make it simple for other drivers, the throttle code has been put in
> separate files.
>
> v1 -> v2:
>
> -Fixed FsContext redeclaration issue
> -Removed couple of function declarations from 9p-throttle.h
> -Fixed some of the .help messages
>
> v2 -> v3:
>
> -Addressed follwing comments by Claudio Fontana
> -Removed redundant memset calls in fsdev_throttle_configure_iolimits function
> -Checking throttle structure validity before initializing other structures
> in fsdev_throttle_configure_iolimits
>
> -Addressed following comments by Greg Kurz
> -Moved the code from 9pfs directory to fsdev directory, because the
> throttling
> is for the fsdev devices.Renamed the files and functions to fsdev_ from
> 9pfs_
> -Renamed throttling cli options to throttling.*, as in QMP cli options
> -Removed some of the unwanted .h files from qemu-fsdev-throttle.[ch]
> -Using throttle_enabled() function to set the thottle enabled flag for fsdev.
>
> diff --git a/fsdev/Makefile.objs b/fsdev/Makefile.objs
> index 1b120a4..2c6da2d 100644
> --- a/fsdev/Makefile.objs
> +++ b/fsdev/Makefile.objs
> @@ -7,6 +7,7 @@ common-obj-y = qemu-fsdev-dummy.o
> endif
> common-obj-y += qemu-fsdev-opts.o
>
> +common-obj-y += qemu-fsdev-throttle.o
> # Toplevel always builds this; targets without virtio will put it in
> # common-obj-y
> common-obj-$(CONFIG_ALL) += qemu-fsdev-dummy.o
> diff --git a/fsdev/file-op-9p.h b/fsdev/file-op-9p.h
> index 6db9fea..33fe822 100644
> --- a/fsdev/file-op-9p.h
> +++ b/fsdev/file-op-9p.h
> @@ -17,6 +17,7 @@
> #include <dirent.h>
> #include <utime.h>
> #include <sys/vfs.h>
> +#include "qemu-fsdev-throttle.h"
>
> #define SM_LOCAL_MODE_BITS 0600
> #define SM_LOCAL_DIR_MODE_BITS 0700
> @@ -74,6 +75,7 @@ typedef struct FsDriverEntry {
> char *path;
> int export_flags;
> FileOperations *ops;
> + FsThrottle fst;
> } FsDriverEntry;
>
> typedef struct FsContext
> @@ -83,6 +85,7 @@ typedef struct FsContext
> int export_flags;
> struct xattr_operations **xops;
> struct extended_ops exops;
> + FsThrottle *fst;
> /* fs driver specific data */
> void *private;
> } FsContext;
> diff --git a/fsdev/qemu-fsdev-opts.c b/fsdev/qemu-fsdev-opts.c
> index 1dd8c7a..395d497 100644
> --- a/fsdev/qemu-fsdev-opts.c
> +++ b/fsdev/qemu-fsdev-opts.c
> @@ -37,6 +37,82 @@ static QemuOptsList qemu_fsdev_opts = {
> }, {
> .name = "sock_fd",
> .type = QEMU_OPT_NUMBER,
> + }, {
> + .name = "throttling.iops-total",
> + .type = QEMU_OPT_NUMBER,
> + .help = "limit total I/O operations per second",
> + },{
> + .name = "throttling.iops-read",
> + .type = QEMU_OPT_NUMBER,
> + .help = "limit read operations per second",
> + },{
> + .name = "throttling.iops-write",
> + .type = QEMU_OPT_NUMBER,
> + .help = "limit write operations per second",
> + },{
> + .name = "throttling.bps-total",
> + .type = QEMU_OPT_NUMBER,
> + .help = "limit total bytes per second",
> + },{
> + .name = "throttling.bps-read",
> + .type = QEMU_OPT_NUMBER,
> + .help = "limit read bytes per second",
> + },{
> + .name = "throttling.bps-write",
> + .type = QEMU_OPT_NUMBER,
> + .help = "limit write bytes per second",
> + },{
> + .name = "throttling.iops-total-max",
> + .type = QEMU_OPT_NUMBER,
> + .help = "I/O operations burst",
> + },{
> + .name = "throttling.iops-read-max",
> + .type = QEMU_OPT_NUMBER,
> + .help = "I/O operations read burst",
> + },{
> + .name = "throttling.iops-write-max",
> + .type = QEMU_OPT_NUMBER,
> + .help = "I/O operations write burst",
> + },{
> + .name = "throttling.bps-total-max",
> + .type = QEMU_OPT_NUMBER,
> + .help = "total bytes burst",
> + },{
> + .name = "throttling.bps-read-max",
> + .type = QEMU_OPT_NUMBER,
> + .help = "total bytes read burst",
> + },{
> + .name = "throttling.bps-write-max",
> + .type = QEMU_OPT_NUMBER,
> + .help = "total bytes write burst",
> + },{
> + .name = "throttling.iops-total-max-length",
> + .type = QEMU_OPT_NUMBER,
> + .help = "length of the iops-total-max burst period, in seconds",
> + },{
> + .name = "throttling.iops-read-max-length",
> + .type = QEMU_OPT_NUMBER,
> + .help = "length of the iops-read-max burst period, in seconds",
> + },{
> + .name = "throttling.iops-write-max-length",
> + .type = QEMU_OPT_NUMBER,
> + .help = "length of the iops-write-max burst period, in seconds",
> + },{
> + .name = "throttling.bps-total-max-length",
> + .type = QEMU_OPT_NUMBER,
> + .help = "length of the bps-total-max burst period, in seconds",
> + },{
> + .name = "throttling.bps-read-max-length",
> + .type = QEMU_OPT_NUMBER,
> + .help = "length of the bps-read-max burst period, in seconds",
> + },{
> + .name = "throttling.bps-write-max-length",
> + .type = QEMU_OPT_NUMBER,
> + .help = "length of the bps-write-max burst period, in seconds",
> + },{
> + .name = "throttling.iops-size",
> + .type = QEMU_OPT_NUMBER,
> + .help = "when limiting by iops max size of an I/O in bytes",
> },
>
> { /*End of list */ }
> diff --git a/fsdev/qemu-fsdev-throttle.c b/fsdev/qemu-fsdev-throttle.c
> new file mode 100644
> index 0000000..0adccd1
> --- /dev/null
> +++ b/fsdev/qemu-fsdev-throttle.c
> @@ -0,0 +1,191 @@
> +/*
> + * Fsdev Throttle
> + *
> + * Copyright (C) 2016 Huawei Technologies Duesseldorf GmbH
> + *
> + * Author: Pradeep Jagadeesh <address@hidden>
> + *
> + * This work is licensed under the terms of the GNU GPL, version 2 or
> + * (at your option) any later version.
> + *
> + * See the COPYING file in the top-level directory for details.
> + *
> + */
> +
> +#include "qemu/osdep.h"
> +#include "qemu/error-report.h"
> +#include "qapi/error.h"
> +#include "qemu-fsdev-throttle.h"
> +
> +static bool fsdev_throttle_check_for_wait(FsThrottle *fst, bool is_write)
> +{
> + if (fst->any_timer_armed[is_write]) {
> + return true;
> + } else {
> + return throttle_schedule_timer(&fst->ts, &fst->tt, is_write);
> + }
> +}
> +
> +static void fsdev_throttle_schedule_next_request(FsThrottle *fst, bool
> is_write)
> +{
> + bool must_wait = fsdev_throttle_check_for_wait(fst, is_write);
Let's add a newline here.
> + if (!fst->pending_reqs[is_write]) {
> + return;
> + }
> + if (!must_wait) {
> + if (qemu_in_coroutine() &&
> + qemu_co_queue_next(&fst->throttled_reqs[is_write])) {
> + ;
> + } else {
> + int64_t now = qemu_clock_get_ns(fst->tt.clock_type);
> + timer_mod(fst->tt.timers[is_write], now + 1);
> + fst->any_timer_armed[is_write] = true;
> + }
> + }
> +}
> +
> +static void fsdev_throttle_timer_cb(FsThrottle *fst, bool is_write)
> +{
> + bool empty_queue;
Same here.
> + qemu_mutex_lock(&fst->lock);
> + fst->any_timer_armed[is_write] = false;
> + qemu_mutex_unlock(&fst->lock);
> + empty_queue = !qemu_co_enter_next(&fst->throttled_reqs[is_write]);
> + if (empty_queue) {
> + qemu_mutex_lock(&fst->lock);
> + fsdev_throttle_schedule_next_request(fst, is_write);
> + qemu_mutex_unlock(&fst->lock);
> + }
> +}
> +
> +bool fsdev_throttle_enabled(FsThrottle *fst)
> +{
> + return fst->enabled;
> +}
> +
> +static void fsdev_iolimits_enable(FsThrottle *fst)
> +{
> + fst->enabled = true;
> +}
> +
> +static void fsdev_iolimits_disable(FsThrottle *fst)
> +{
> + fst->enabled = false;
> +}
> +
fsdev_throttle_configure_iolimits() is the only function that will ever
write to fst->enabled. The helpers seem to indicate the opposite. It is
better to open code in fsdev_throttle_configure_iolimits().
> +static void fsdev_throttle_read_timer_cb(void *opaque)
> +{
> + fsdev_throttle_timer_cb(opaque, false);
> +}
> +
> +static void fsdev_throttle_write_timer_cb(void *opaque)
> +{
> + fsdev_throttle_timer_cb(opaque, true);
> +}
> +
> +static void fsdev_parse_io_limit_opts(QemuOpts *opts, FsThrottle *fst)
> +{
> + fst->cfg.buckets[THROTTLE_BPS_TOTAL].avg =
> + qemu_opt_get_number(opts, "throttling.bps-total", 0);
> + fst->cfg.buckets[THROTTLE_BPS_READ].avg =
> + qemu_opt_get_number(opts, "throttling.bps-read", 0);
> + fst->cfg.buckets[THROTTLE_BPS_WRITE].avg =
> + qemu_opt_get_number(opts, "throttling.bps-write", 0);
> + fst->cfg.buckets[THROTTLE_OPS_TOTAL].avg =
> + qemu_opt_get_number(opts, "throttling.iops-total", 0);
> + fst->cfg.buckets[THROTTLE_OPS_READ].avg =
> + qemu_opt_get_number(opts, "throttling.iops-read", 0);
> + fst->cfg.buckets[THROTTLE_OPS_WRITE].avg =
> + qemu_opt_get_number(opts, "throttling.iops-write", 0);
> +
> + fst->cfg.buckets[THROTTLE_BPS_TOTAL].max =
> + qemu_opt_get_number(opts, "throttling.bps-total-max", 0);
> + fst->cfg.buckets[THROTTLE_BPS_READ].max =
> + qemu_opt_get_number(opts, "throttling.bps-read-max", 0);
> + fst->cfg.buckets[THROTTLE_BPS_WRITE].max =
> + qemu_opt_get_number(opts, "throttling.bps-write-max", 0);
> + fst->cfg.buckets[THROTTLE_OPS_TOTAL].max =
> + qemu_opt_get_number(opts, "throttling.iops-total-max", 0);
> + fst->cfg.buckets[THROTTLE_OPS_READ].max =
> + qemu_opt_get_number(opts, "throttling.iops-read-max", 0);
> + fst->cfg.buckets[THROTTLE_OPS_WRITE].max =
> + qemu_opt_get_number(opts, "throttling.iops-write-max", 0);
> +
> + fst->cfg.buckets[THROTTLE_BPS_TOTAL].burst_length =
> + qemu_opt_get_number(opts, "throttling.bps-total-max-length", 1);
> + fst->cfg.buckets[THROTTLE_BPS_READ].burst_length =
> + qemu_opt_get_number(opts, "throttling.bps-read-max-length", 1);
> + fst->cfg.buckets[THROTTLE_BPS_WRITE].burst_length =
> + qemu_opt_get_number(opts, "throttling.bps-write-max-length", 1);
> + fst->cfg.buckets[THROTTLE_OPS_TOTAL].burst_length =
> + qemu_opt_get_number(opts, "throttling.iops-total-max-length", 1);
> + fst->cfg.buckets[THROTTLE_OPS_READ].burst_length =
> + qemu_opt_get_number(opts, "throttling.iops-read-max-length", 1);
> + fst->cfg.buckets[THROTTLE_OPS_WRITE].burst_length =
> + qemu_opt_get_number(opts, "throttling.iops-write-max-length", 1);
> + fst->cfg.op_size =
> + qemu_opt_get_number(opts, "throttling.iops-size", 0);
> +}
> +
> +int fsdev_throttle_configure_iolimits(QemuOpts *opts, FsThrottle *fst)
> +{
> + Error *err = NULL;
> +
> + /* Parse and set populate the cfg structure */
> + fsdev_parse_io_limit_opts(opts, fst);
> +
> + if (!throttle_is_valid(&fst->cfg, &err)) {
> + error_report("Throttle configuration is not valid");
throttle_is_valid() already populates err with a meaningful message and
you should use it:
error_reportf_err(err, "Throttle configuration is not valid: ");
> + return -1;
> + }
> + if (throttle_enabled(&fst->cfg)) {
> + fst->aioctx = qemu_get_aio_context();
> + if (!fst->aioctx) {
> + error_report("Failed to create AIO Context");
> + return -1;
> + }
qemu_get_aio_context() returns qemu_aio_context which is initialized in
qemu_init_main_loop(). It is guarantied to be non NULL and if it is, we'd
better dump core.
> + throttle_init(&fst->ts);
> + throttle_timers_init(&fst->tt,
> + fst->aioctx,
> + QEMU_CLOCK_REALTIME,
> + fsdev_throttle_read_timer_cb,
> + fsdev_throttle_write_timer_cb,
> + fst);
> + throttle_config(&fst->ts, &fst->tt, &fst->cfg);
> + qemu_co_queue_init(&fst->throttled_reqs[0]);
> + qemu_co_queue_init(&fst->throttled_reqs[1]);
> + fst->pending_reqs[0] = 0;
> + fst->pending_reqs[1] = 0;
> + fst->any_timer_armed[0] = false;
> + fst->any_timer_armed[1] = false;
> + qemu_mutex_init(&fst->lock);
> + fsdev_iolimits_enable(fst);
> + } else {
> + fsdev_iolimits_disable(fst);
> + }
> + return 0;
> +}
> +
> +void fsdev_throttle_request(FsThrottle *fst, bool is_write, ssize_t bytes)
> +{
> + if (fsdev_throttle_enabled(fst)) {
> + qemu_mutex_lock(&fst->lock);
> + bool must_wait = fsdev_throttle_check_for_wait(fst, is_write);
Even if the QEMU code is supposed to follow C99, I think it is prettier to
declare variables at the beginning of the code block.
bool must_wait;
qemu_mutex_lock(&fst->lock);
must_wait = fsdev_throttle_check_for_wait(fst, is_write);
> + if (must_wait || fst->pending_reqs[is_write]) {
> + fst->pending_reqs[is_write]++;
> + qemu_mutex_unlock(&fst->lock);
> + qemu_co_queue_wait(&fst->throttled_reqs[is_write]);
> + qemu_mutex_lock(&fst->lock);
> + fst->pending_reqs[is_write]--;
> + }
> + throttle_account(&fst->ts, is_write, bytes);
> + fsdev_throttle_schedule_next_request(fst, is_write);
> + qemu_mutex_unlock(&fst->lock);
> + }
> +}
> +
> +void fsdev_throttle_cleanup(FsThrottle *fst)
> +{
> + throttle_timers_destroy(&fst->tt);
> + qemu_mutex_destroy(&fst->lock);
> +}
> diff --git a/fsdev/qemu-fsdev-throttle.h b/fsdev/qemu-fsdev-throttle.h
> new file mode 100644
> index 0000000..73dd367
> --- /dev/null
> +++ b/fsdev/qemu-fsdev-throttle.h
> @@ -0,0 +1,42 @@
> +/*
> + * Fsdev Throttle
> + *
> + * Copyright (C) 2016 Huawei Technologies Duesseldorf GmbH
> + *
> + * Author: Pradeep Jagadeesh <address@hidden>
> + *
> + * This work is licensed under the terms of the GNU GPL, version 2 or
> + * (at your option) any later version.
> + *
> + * See the COPYING file in the top-level directory for details.
> + *
> + */
> +
> +#ifndef _FSDEV_THROTTLE_H
> +#define _FSDEV_THROTTLE_H
> +
> +#include "block/aio.h"
> +#include "qemu/main-loop.h"
> +#include "qemu/coroutine.h"
> +#include "qemu/throttle.h"
> +
> +typedef struct FsThrottle {
> + ThrottleState ts;
> + ThrottleTimers tt;
> + AioContext *aioctx;
> + ThrottleConfig cfg;
> + bool enabled;
> + CoQueue throttled_reqs[2];
> + unsigned pending_reqs[2];
> + bool any_timer_armed[2];
> + QemuMutex lock;
> +} FsThrottle;
> +
> +bool fsdev_throttle_enabled(FsThrottle *);
> +
> +int fsdev_throttle_configure_iolimits(QemuOpts *, FsThrottle *);
> +
> +void fsdev_throttle_request(FsThrottle *, bool , ssize_t);
> +
> +void fsdev_throttle_cleanup(FsThrottle *);
> +#endif /* _FSDEV_THROTTLE_H */
> diff --git a/hw/9pfs/9p-local.c b/hw/9pfs/9p-local.c
> index 3f271fc..b1009fc 100644
> --- a/hw/9pfs/9p-local.c
> +++ b/hw/9pfs/9p-local.c
> @@ -436,8 +436,8 @@ static ssize_t local_pwritev(FsContext *ctx,
> V9fsFidOpenState *fs,
> const struct iovec *iov,
> int iovcnt, off_t offset)
> {
> - ssize_t ret
> -;
> + ssize_t ret;
> +
> #ifdef CONFIG_PREADV
> ret = pwritev(fs->fd, iov, iovcnt, offset);
> #else
> @@ -1213,6 +1213,8 @@ static int local_parse_opts(QemuOpts *opts, struct
> FsDriverEntry *fse)
> const char *sec_model = qemu_opt_get(opts, "security_model");
> const char *path = qemu_opt_get(opts, "path");
>
> + FsThrottle *fst = &fse->fst;
> +
> if (!sec_model) {
> error_report("Security model not specified, local fs needs security
> model");
> error_printf("valid options are:"
> @@ -1240,6 +1242,11 @@ static int local_parse_opts(QemuOpts *opts, struct
> FsDriverEntry *fse)
> error_report("fsdev: No path specified");
> return -1;
> }
> +
> + if (fsdev_throttle_configure_iolimits(opts, fst) < 0) {
> + return -1;
> + }
> +
> fse->path = g_strdup(path);
>
> return 0;
> diff --git a/hw/9pfs/9p.c b/hw/9pfs/9p.c
> index dfe293d..3748ba9 100644
> --- a/hw/9pfs/9p.c
> +++ b/hw/9pfs/9p.c
> @@ -3490,6 +3490,10 @@ int v9fs_device_realize_common(V9fsState *s, Error
> **errp)
> error_setg(errp, "share path %s is not a directory", fse->path);
> goto out;
> }
> +
> + /* Throttle structure initialization */
I'm still thinking this comment paraphrases the code :)
> + s->ctx.fst = &fse->fst;
> +
> v9fs_path_free(&path);
>
> rc = 0;
> @@ -3504,6 +3508,9 @@ out:
>
> void v9fs_device_unrealize_common(V9fsState *s, Error **errp)
> {
> + if (fsdev_throttle_enabled(s->ctx.fst)) {
> + fsdev_throttle_cleanup(s->ctx.fst);
> + }
> g_free(s->ctx.fs_root);
> g_free(s->tag);
> }
> diff --git a/hw/9pfs/cofile.c b/hw/9pfs/cofile.c
> index 10343c0..65897d5 100644
> --- a/hw/9pfs/cofile.c
> +++ b/hw/9pfs/cofile.c
> @@ -16,6 +16,7 @@
> #include "qemu/thread.h"
> #include "qemu/coroutine.h"
> #include "coth.h"
> +#include "fsdev/qemu-fsdev-throttle.h"
>
> int v9fs_co_st_gen(V9fsPDU *pdu, V9fsPath *path, mode_t st_mode,
> V9fsStatDotl *v9stat)
> @@ -242,6 +243,7 @@ int v9fs_co_pwritev(V9fsPDU *pdu, V9fsFidState *fidp,
> int err;
> V9fsState *s = pdu->s;
>
> + fsdev_throttle_request(s->ctx.fst, true, iov->iov_len);
I think it would make more sense to move this after the cancellation point.
> if (v9fs_request_cancelled(pdu)) {
> return -EINTR;
> }
> @@ -261,6 +263,7 @@ int v9fs_co_preadv(V9fsPDU *pdu, V9fsFidState *fidp,
> int err;
> V9fsState *s = pdu->s;
>
> + fsdev_throttle_request(s->ctx.fst, false, iov->iov_len);
Same here.
> if (v9fs_request_cancelled(pdu)) {
> return -EINTR;
> }
Cheers.
--
Greg