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Date: Tue, 7 Dec 2021 10:07:45 +0100
From: Miklos Szeredi <miklos@...redi.hu>
To: Ingo Molnar <mingo@...hat.com>,
Peter Zijlstra <peterz@...radead.org>
Cc: quic_stummala@...cinc.com, linux-kernel@...r.kernel.org,
linux-fsdevel@...r.kernel.org, quic_pkondeti@...cinc.com,
quic_sayalil@...cinc.com, quic_aiquny@...cinc.com,
quic_zljing@...cinc.com, quic_blong@...cinc.com,
quic_richardp@...cinc.com, quic_cdevired@...cinc.com,
Pradeep P V K <quic_pragalla@...cinc.com>
Subject: Re: [PATCH V1] fuse: give wakeup hints to the scheduler
On Mon, 6 Dec 2021 at 09:47, Pradeep P V K <quic_pragalla@...cinc.com> wrote:
>
> The synchronous wakeup interface is available only for the
> interruptible wakeup. Add it for normal wakeup and use this
> synchronous wakeup interface to wakeup the userspace daemon.
> Scheduler can make use of this hint to find a better CPU for
> the waker task.
Ingo, Peter,
What exactly does WF_SYNC do? Does it try to give the waker's CPU
immediately to the waked?
If that doesn't work (e.g. in this patch the wake up is done with a
spin lock held) does it do anything?
Does it give a hint that the waked task should be scheduled on this
CPU at the next scheduling point?
Thanks,
Miklos
>
> With this change the performance numbers for compress, decompress
> and copy use-cases on /sdcard path has improved by ~30%.
>
> Use-case details:
> 1. copy 10000 files of each 4k size into /sdcard path
> 2. use any File explorer application that has compress/decompress
> support
> 3. start compress/decompress and capture the time.
>
> -------------------------------------------------
> | Default | wakeup support | Improvement/Diff |
> -------------------------------------------------
> | 13.8 sec | 9.9 sec | 3.9 sec (28.26%) |
> -------------------------------------------------
>
> Co-developed-by: Pavankumar Kondeti <quic_pkondeti@...cinc.com>
> Signed-off-by: Pradeep P V K <quic_pragalla@...cinc.com>
> ---
> fs/fuse/dev.c | 22 +++++++++++++---------
> fs/fuse/fuse_i.h | 6 +++---
> fs/fuse/virtio_fs.c | 8 +++++---
> include/linux/wait.h | 1 +
> 4 files changed, 22 insertions(+), 15 deletions(-)
>
> diff --git a/fs/fuse/dev.c b/fs/fuse/dev.c
> index cd54a52..fef2e23 100644
> --- a/fs/fuse/dev.c
> +++ b/fs/fuse/dev.c
> @@ -207,10 +207,13 @@ static unsigned int fuse_req_hash(u64 unique)
> /**
> * A new request is available, wake fiq->waitq
> */
> -static void fuse_dev_wake_and_unlock(struct fuse_iqueue *fiq)
> +static void fuse_dev_wake_and_unlock(struct fuse_iqueue *fiq, bool sync)
> __releases(fiq->lock)
> {
> - wake_up(&fiq->waitq);
> + if (sync)
> + wake_up_sync(&fiq->waitq);
> + else
> + wake_up(&fiq->waitq);
> kill_fasync(&fiq->fasync, SIGIO, POLL_IN);
> spin_unlock(&fiq->lock);
> }
> @@ -223,14 +226,15 @@ const struct fuse_iqueue_ops fuse_dev_fiq_ops = {
> EXPORT_SYMBOL_GPL(fuse_dev_fiq_ops);
>
> static void queue_request_and_unlock(struct fuse_iqueue *fiq,
> - struct fuse_req *req)
> + struct fuse_req *req,
> + bool sync)
> __releases(fiq->lock)
> {
> req->in.h.len = sizeof(struct fuse_in_header) +
> fuse_len_args(req->args->in_numargs,
> (struct fuse_arg *) req->args->in_args);
> list_add_tail(&req->list, &fiq->pending);
> - fiq->ops->wake_pending_and_unlock(fiq);
> + fiq->ops->wake_pending_and_unlock(fiq, sync);
> }
>
> void fuse_queue_forget(struct fuse_conn *fc, struct fuse_forget_link *forget,
> @@ -245,7 +249,7 @@ void fuse_queue_forget(struct fuse_conn *fc, struct fuse_forget_link *forget,
> if (fiq->connected) {
> fiq->forget_list_tail->next = forget;
> fiq->forget_list_tail = forget;
> - fiq->ops->wake_forget_and_unlock(fiq);
> + fiq->ops->wake_forget_and_unlock(fiq, 0);
> } else {
> kfree(forget);
> spin_unlock(&fiq->lock);
> @@ -265,7 +269,7 @@ static void flush_bg_queue(struct fuse_conn *fc)
> fc->active_background++;
> spin_lock(&fiq->lock);
> req->in.h.unique = fuse_get_unique(fiq);
> - queue_request_and_unlock(fiq, req);
> + queue_request_and_unlock(fiq, req, 0);
> }
> }
>
> @@ -358,7 +362,7 @@ static int queue_interrupt(struct fuse_req *req)
> spin_unlock(&fiq->lock);
> return 0;
> }
> - fiq->ops->wake_interrupt_and_unlock(fiq);
> + fiq->ops->wake_interrupt_and_unlock(fiq, 0);
> } else {
> spin_unlock(&fiq->lock);
> }
> @@ -425,7 +429,7 @@ static void __fuse_request_send(struct fuse_req *req)
> /* acquire extra reference, since request is still needed
> after fuse_request_end() */
> __fuse_get_request(req);
> - queue_request_and_unlock(fiq, req);
> + queue_request_and_unlock(fiq, req, 1);
>
> request_wait_answer(req);
> /* Pairs with smp_wmb() in fuse_request_end() */
> @@ -600,7 +604,7 @@ static int fuse_simple_notify_reply(struct fuse_mount *fm,
>
> spin_lock(&fiq->lock);
> if (fiq->connected) {
> - queue_request_and_unlock(fiq, req);
> + queue_request_and_unlock(fiq, req, 0);
> } else {
> err = -ENODEV;
> spin_unlock(&fiq->lock);
> diff --git a/fs/fuse/fuse_i.h b/fs/fuse/fuse_i.h
> index c1a8b31..363e0ba 100644
> --- a/fs/fuse/fuse_i.h
> +++ b/fs/fuse/fuse_i.h
> @@ -389,19 +389,19 @@ struct fuse_iqueue_ops {
> /**
> * Signal that a forget has been queued
> */
> - void (*wake_forget_and_unlock)(struct fuse_iqueue *fiq)
> + void (*wake_forget_and_unlock)(struct fuse_iqueue *fiq, bool sync)
> __releases(fiq->lock);
>
> /**
> * Signal that an INTERRUPT request has been queued
> */
> - void (*wake_interrupt_and_unlock)(struct fuse_iqueue *fiq)
> + void (*wake_interrupt_and_unlock)(struct fuse_iqueue *fiq, bool sync)
> __releases(fiq->lock);
>
> /**
> * Signal that a request has been queued
> */
> - void (*wake_pending_and_unlock)(struct fuse_iqueue *fiq)
> + void (*wake_pending_and_unlock)(struct fuse_iqueue *fiq, bool sync)
> __releases(fiq->lock);
>
> /**
> diff --git a/fs/fuse/virtio_fs.c b/fs/fuse/virtio_fs.c
> index 4cfa4bc..bdc3dcc 100644
> --- a/fs/fuse/virtio_fs.c
> +++ b/fs/fuse/virtio_fs.c
> @@ -972,7 +972,7 @@ static struct virtio_driver virtio_fs_driver = {
> #endif
> };
>
> -static void virtio_fs_wake_forget_and_unlock(struct fuse_iqueue *fiq)
> +static void virtio_fs_wake_forget_and_unlock(struct fuse_iqueue *fiq, bool sync)
> __releases(fiq->lock)
> {
> struct fuse_forget_link *link;
> @@ -1007,7 +1007,8 @@ __releases(fiq->lock)
> kfree(link);
> }
>
> -static void virtio_fs_wake_interrupt_and_unlock(struct fuse_iqueue *fiq)
> +static void virtio_fs_wake_interrupt_and_unlock(struct fuse_iqueue *fiq,
> + bool sync)
> __releases(fiq->lock)
> {
> /*
> @@ -1222,7 +1223,8 @@ static int virtio_fs_enqueue_req(struct virtio_fs_vq *fsvq,
> return ret;
> }
>
> -static void virtio_fs_wake_pending_and_unlock(struct fuse_iqueue *fiq)
> +static void virtio_fs_wake_pending_and_unlock(struct fuse_iqueue *fiq,
> + bool sync)
> __releases(fiq->lock)
> {
> unsigned int queue_id = VQ_REQUEST; /* TODO multiqueue */
> diff --git a/include/linux/wait.h b/include/linux/wait.h
> index 2d0df57..690572ee 100644
> --- a/include/linux/wait.h
> +++ b/include/linux/wait.h
> @@ -228,6 +228,7 @@ void __wake_up_sync(struct wait_queue_head *wq_head, unsigned int mode);
> #define wake_up_interruptible_nr(x, nr) __wake_up(x, TASK_INTERRUPTIBLE, nr, NULL)
> #define wake_up_interruptible_all(x) __wake_up(x, TASK_INTERRUPTIBLE, 0, NULL)
> #define wake_up_interruptible_sync(x) __wake_up_sync((x), TASK_INTERRUPTIBLE)
> +#define wake_up_sync(x) __wake_up_sync(x, TASK_NORMAL)
>
> /*
> * Wakeup macros to be used to report events to the targets.
> --
> 2.7.4
>
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