Re: [PATCH v2] fuse: optimize over-io-uring request expiration check

[Bernd Schubert <bernd@bsbernd.com>]

On 2/3/25 20:37, Joanne Koong wrote:
> On Mon, Feb 3, 2025 at 11:30 AM Joanne Koong <joannelkoong@gmail.com> wrote:
>>
>> Currently, when checking whether a request has timed out, we check
>> fpq processing, but fuse-over-io-uring has one fpq per core and 256
>> entries in the processing table. For systems where there are a
>> large number of cores, this may be too much overhead.
>>
>> Instead of checking the fpq processing list, check ent_w_req_queue
>> and ent_in_userspace.
>>
>> Signed-off-by: Joanne Koong <joannelkoong@gmail.com>
>> ---
>>  fs/fuse/dev.c        |  2 +-
>>  fs/fuse/dev_uring.c  | 26 +++++++++++++++++++++-----
>>  fs/fuse/fuse_dev_i.h |  1 -
>>  3 files changed, 22 insertions(+), 7 deletions(-)
>>
> 
> v1: https://lore.kernel.org/linux-fsdevel/20250123235251.1139078-1-joannelkoong@gmail.com/
> Changes from v1 -> v2:
> * Remove commit queue check, which should be fine since if the request
> has expired while on this queue, it will be shortly processed anyways
> 
>> diff --git a/fs/fuse/dev.c b/fs/fuse/dev.c
>> index 3c03aac480a4..80a11ef4b69a 100644
>> --- a/fs/fuse/dev.c
>> +++ b/fs/fuse/dev.c
>> @@ -45,7 +45,7 @@ bool fuse_request_expired(struct fuse_conn *fc, struct list_head *list)
>>         return time_is_before_jiffies(req->create_time + fc->timeout.req_timeout);
>>  }
>>
>> -bool fuse_fpq_processing_expired(struct fuse_conn *fc, struct list_head *processing)
>> +static bool fuse_fpq_processing_expired(struct fuse_conn *fc, struct list_head *processing)
>>  {
>>         int i;
>>
>> diff --git a/fs/fuse/dev_uring.c b/fs/fuse/dev_uring.c
>> index ab8c26042aa8..50f5b4e32ed5 100644
>> --- a/fs/fuse/dev_uring.c
>> +++ b/fs/fuse/dev_uring.c
>> @@ -140,6 +140,21 @@ void fuse_uring_abort_end_requests(struct fuse_ring *ring)
>>         }
>>  }
>>
>> +static bool ent_list_request_expired(struct fuse_conn *fc, struct list_head *list)
>> +{
>> +       struct fuse_ring_ent *ent;
>> +       struct fuse_req *req;
>> +
>> +       ent = list_first_entry_or_null(list, struct fuse_ring_ent, list);
>> +       if (!ent)
>> +               return false;
>> +
>> +       req = ent->fuse_req;
>> +
>> +       return time_is_before_jiffies(req->create_time +
>> +                                     fc->timeout.req_timeout);
>> +}
>> +
>>  bool fuse_uring_request_expired(struct fuse_conn *fc)
>>  {
>>         struct fuse_ring *ring = fc->ring;
>> @@ -157,7 +172,8 @@ bool fuse_uring_request_expired(struct fuse_conn *fc)
>>                 spin_lock(&queue->lock);
>>                 if (fuse_request_expired(fc, &queue->fuse_req_queue) ||
>>                     fuse_request_expired(fc, &queue->fuse_req_bg_queue) ||
>> -                   fuse_fpq_processing_expired(fc, queue->fpq.processing)) {
>> +                   ent_list_request_expired(fc, &queue->ent_w_req_queue) ||
>> +                   ent_list_request_expired(fc, &queue->ent_in_userspace)) {
>>                         spin_unlock(&queue->lock);
>>                         return true;
>>                 }
>> @@ -495,7 +511,7 @@ static void fuse_uring_cancel(struct io_uring_cmd *cmd,
>>         spin_lock(&queue->lock);
>>         if (ent->state == FRRS_AVAILABLE) {
>>                 ent->state = FRRS_USERSPACE;
>> -               list_move(&ent->list, &queue->ent_in_userspace);
>> +               list_move_tail(&ent->list, &queue->ent_in_userspace);
>>                 need_cmd_done = true;
>>                 ent->cmd = NULL;
>>         }
>> @@ -715,7 +731,7 @@ static int fuse_uring_send_next_to_ring(struct fuse_ring_ent *ent,
>>         cmd = ent->cmd;
>>         ent->cmd = NULL;
>>         ent->state = FRRS_USERSPACE;
>> -       list_move(&ent->list, &queue->ent_in_userspace);
>> +       list_move_tail(&ent->list, &queue->ent_in_userspace);
>>         spin_unlock(&queue->lock);
>>
>>         io_uring_cmd_done(cmd, 0, 0, issue_flags);
>> @@ -769,7 +785,7 @@ static void fuse_uring_add_req_to_ring_ent(struct fuse_ring_ent *ent,
>>         spin_unlock(&fiq->lock);
>>         ent->fuse_req = req;
>>         ent->state = FRRS_FUSE_REQ;
>> -       list_move(&ent->list, &queue->ent_w_req_queue);
>> +       list_move_tail(&ent->list, &queue->ent_w_req_queue);
>>         fuse_uring_add_to_pq(ent, req);
>>  }
>>
>> @@ -1185,7 +1201,7 @@ static void fuse_uring_send(struct fuse_ring_ent *ent, struct io_uring_cmd *cmd,
>>
>>         spin_lock(&queue->lock);
>>         ent->state = FRRS_USERSPACE;
>> -       list_move(&ent->list, &queue->ent_in_userspace);
>> +       list_move_tail(&ent->list, &queue->ent_in_userspace);
>>         ent->cmd = NULL;
>>         spin_unlock(&queue->lock);
>>
>> diff --git a/fs/fuse/fuse_dev_i.h b/fs/fuse/fuse_dev_i.h
>> index 3c4ae4d52b6f..19c29c6000a7 100644
>> --- a/fs/fuse/fuse_dev_i.h
>> +++ b/fs/fuse/fuse_dev_i.h
>> @@ -63,7 +63,6 @@ void fuse_dev_queue_forget(struct fuse_iqueue *fiq,
>>  void fuse_dev_queue_interrupt(struct fuse_iqueue *fiq, struct fuse_req *req);
>>
>>  bool fuse_request_expired(struct fuse_conn *fc, struct list_head *list);
>> -bool fuse_fpq_processing_expired(struct fuse_conn *fc, struct list_head *processing);
>>
>>  #endif
>>
>> --
>> 2.43.5
>>
> 


Reviewed-by: Bernd Schubert <bernd@bsbernd.com>