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Re: [Qemu-devel] [V7 1/1] fsdev: add IO throttle support to fsdev device
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From: |
Greg Kurz |
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Subject: |
Re: [Qemu-devel] [V7 1/1] fsdev: add IO throttle support to fsdev devices |
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Date: |
Sun, 30 Oct 2016 14:35:52 +0100 |
On Sun, 30 Oct 2016 14:04:49 +0100
Pradeep Jagadeesh <address@hidden> wrote:
> >> More remarks below.
> >>
> >>> fsdev/Makefile.objs | 1 +
> >>> fsdev/file-op-9p.h | 3 +
> >>> fsdev/qemu-fsdev-opts.c | 76 +++++++++++++++++++++++
> >>> fsdev/qemu-fsdev-throttle.c | 147
> >>> ++++++++++++++++++++++++++++++++++++++++++++
> >>> fsdev/qemu-fsdev-throttle.h | 37 +++++++++++
> >>> hw/9pfs/9p-local.c | 9 ++-
> >>> hw/9pfs/9p.c | 6 ++
> >>> hw/9pfs/cofile.c | 5 ++
> >>> 8 files changed, 282 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.
> >>>
> >>
> >> The above lines are the changelog for the patch. We want this to be
> >> displayed
> >> when running 'git log'. For this to happen, please move these lines
> >> above your
> >> SoB tag.
> OK
> >>
> >> Only the vN -> vN+1 changes are not relevant (we don't need to record
> >> all the
> >> intermediate reviews in git) and should stay here.
> >>
> I just put there just keep track of what comments I fixed from which
> reviewer in recent patches.
> This we can take off when we have the final patch right?
>
> Also I did not understand your comment about vN -> vN+1.
Heh sorry for not being clear :)
I was saying only the v1->v2, v2->v3 (i.e. vN -> vN+1) parts must stay below
the --- so that git am doesn't copy them to the commit log. So, you're good
with this part :)
> >>> 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.
> >>>
> >>> v3 -> v4:
> >>>
> >>> -Addressed following comments by Alberto Garcia
> >>> -Removed the unwanted locking and other data structures in
> >>> qemu-fsdev-throttle.[ch]
> >>>
> >>> -Addressed following comments by Greg Kurz
> >>> -Removed fsdev_iolimitsenable/disable functions, instead using
> >>> throttle_enabled function
> >>>
> >>> v4 -> V5:
> >>> -Fixed the issue with the larger block size accounting.
> >>> (i.e, when the 9pfs mounted using msize=xxx option)
> >>>
> >>> V5 -> V6:
> >>> -Addressed the comments by Alberto Garcia
> >>> -Removed the fsdev_throttle_timer_cb()
> >>> -Simplified the fsdev_throttle_schedule_next_request() as suggested
> >>>
> >>> V6 -> V7:
> >>> -Addressed the comments by Alberto Garcia
> >>> -changed the fsdev_throttle_schedule_next_request() as suggested
> >>>
> >>>
> >>> 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..d48d031
> >>> --- /dev/null
> >>> +++ b/fsdev/qemu-fsdev-throttle.c
> >>> @@ -0,0 +1,147 @@
> >>> +/*
> >>> + * 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)
> >>> +{
> >>> + return throttle_schedule_timer(&fst->ts, &fst->tt, is_write);
> >>> +}
> >>> +
> >>> +static void fsdev_throttle_schedule_next_request(FsThrottle *fst,
> >>> bool is_write)
> >>> +{
> >>> + if (!qemu_co_queue_empty(&fst->throttled_reqs[is_write])) {
> >>> + if (fsdev_throttle_check_for_wait(fst, is_write)) {
> >>> + return;
> >>> + }
> >>> + qemu_co_queue_next(&fst->throttled_reqs[is_write]);
> >>
> >> This calls for a coroutine_fn tag but...
> >>
> >>> + }
> >>> +}
> >>> +
> >>
> >> ... as Berto already suggested in v6, these functions aren't needed
> >> and your
> >> "I just would like to keep these functions" answer isn't convincing
> >> enough.
> >> Personally, I'd greatly really prefer the code to be inlined in the
> >> callers,
> >> so that we can see the whole throttling/queue logic in one place.
> In lined the code fsdev_throttle_check_for_wait().
Cool, thanks!
I'll be AFK most of tomorrow and soft freeze starts next Tuesday... do you
*really* need this to be in 2.8 ?
Cheers.
--
Greg
> >>
> >>> +static void fsdev_throttle_read_timer_cb(void *opaque)
> >>> +{
> >>> + FsThrottle *fst = opaque;
> >>> + qemu_co_enter_next(&fst->throttled_reqs[false]);
> >>> +}
> >>> +
> >>> +static void fsdev_throttle_write_timer_cb(void *opaque)
> >>> +{
> >>> + FsThrottle *fst = opaque;
> >>> + qemu_co_enter_next(&fst->throttled_reqs[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_reportf_err(err, "Throttle configuration is not valid:
> >>> ");
> >>> + return -1;
> >>> + }
> >>> + if (throttle_enabled(&fst->cfg)) {
> >>> + g_assert((fst->aioctx = qemu_get_aio_context()));
> >>> + 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]);
> >>> + }
> >>> + return 0;
> >>> +}
> >>> +
> >>> +static int get_num_bytes(struct iovec *iov, int iovcnt)
> >>> +{
> >>> + int i;
> >>> + unsigned int bytes = 0;
> >>> +
> >>> + for (i = 0; i < iovcnt; i++) {
> >>> + bytes += iov[i].iov_len;
> >>> + }
> >>> + return bytes;
> >>> +}
> >>> +
> >>> +void coroutine_fn fsdev_co_throttle_request(FsThrottle *fst, bool
> >>> is_write,
> >>> + struct iovec *iov, int iovcnt)
> >>> +{
> >>> + if (throttle_enabled(&fst->cfg)) {
> >>> + int bytes = get_num_bytes(iov, iovcnt);
> >>> + bool must_wait = fsdev_throttle_check_for_wait(fst, is_write);
> >>> + if (must_wait ||
> >>> !qemu_co_queue_empty(&fst->throttled_reqs[is_write])) {
> >>> + qemu_co_queue_wait(&fst->throttled_reqs[is_write]);
> >>> + }
> >>> + throttle_account(&fst->ts, is_write, bytes);
> >>> +
> >>> + fsdev_throttle_schedule_next_request(fst, is_write);
> >>> + }
> >>> +}
> >>> +
> >>> +void fsdev_throttle_cleanup(FsThrottle *fst)
> >>> +{
> >>> + throttle_timers_destroy(&fst->tt);
> >>> +}
> >>> diff --git a/fsdev/qemu-fsdev-throttle.h b/fsdev/qemu-fsdev-throttle.h
> >>> new file mode 100644
> >>> index 0000000..df4e608
> >>> --- /dev/null
> >>> +++ b/fsdev/qemu-fsdev-throttle.h
> >>> @@ -0,0 +1,37 @@
> >>> +/*
> >>> + * 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;
> >>> + CoQueue throttled_reqs[2];
> >>> +} FsThrottle;
> >>> +
> >>> +int fsdev_throttle_configure_iolimits(QemuOpts *, FsThrottle *);
> >>> +
> >>> +void coroutine_fn fsdev_co_throttle_request(FsThrottle *fst, bool
> >>> is_write,
> >>> + struct iovec *iov, int iovcnt);
> >>> +
> >>> +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..54459f2 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;
> >>> +
> >>
> >> Please push this to a separate patch.
> OK.
>
> -Pradeep
>
> >>
> >> Thanks.
> >>
> >> --
> >> Greg
> >>
> >>> #ifdef CONFIG_PREADV
> >>> ret = pwritev(fs->fd, iov, iovcnt, offset);
> >>> #else
> >>> @@ -1240,6 +1240,11 @@ static int local_parse_opts(QemuOpts *opts,
> >>> struct FsDriverEntry *fse)
> >>> error_report("fsdev: No path specified");
> >>> return -1;
> >>> }
> >>> +
> >>> + if (fsdev_throttle_configure_iolimits(opts, &fse->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..ccf6d0c 100644
> >>> --- a/hw/9pfs/9p.c
> >>> +++ b/hw/9pfs/9p.c
> >>> @@ -3490,6 +3490,9 @@ int v9fs_device_realize_common(V9fsState *s,
> >>> Error **errp)
> >>> error_setg(errp, "share path %s is not a directory",
> >>> fse->path);
> >>> goto out;
> >>> }
> >>> +
> >>> + s->ctx.fst = &fse->fst;
> >>> +
> >>> v9fs_path_free(&path);
> >>>
> >>> rc = 0;
> >>> @@ -3504,6 +3507,9 @@ out:
> >>>
> >>> void v9fs_device_unrealize_common(V9fsState *s, Error **errp)
> >>> {
> >>> + if (throttle_enabled(&s->ctx.fst->cfg)) {
> >>> + 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..039031d 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)
> >>> @@ -245,6 +246,8 @@ int v9fs_co_pwritev(V9fsPDU *pdu, V9fsFidState
> >>> *fidp,
> >>> if (v9fs_request_cancelled(pdu)) {
> >>> return -EINTR;
> >>> }
> >>> +
> >>> + fsdev_co_throttle_request(s->ctx.fst, true, iov, iovcnt);
> >>> v9fs_co_run_in_worker(
> >>> {
> >>> err = s->ops->pwritev(&s->ctx, &fidp->fs, iov, iovcnt,
> >>> offset);
> >>> @@ -264,6 +267,8 @@ int v9fs_co_preadv(V9fsPDU *pdu, V9fsFidState *fidp,
> >>> if (v9fs_request_cancelled(pdu)) {
> >>> return -EINTR;
> >>> }
> >>> +
> >>> + fsdev_co_throttle_request(s->ctx.fst, false, iov, iovcnt);
> >>> v9fs_co_run_in_worker(
> >>> {
> >>> err = s->ops->preadv(&s->ctx, &fidp->fs, iov, iovcnt,
> >>> offset);
> >>
>