[Devel] [PATCH RHEL9] fs/fuse: make size of qhash and limit of each bucket module parameters

[Alexey Kuznetsov]

Ack

On Thu, Nov 16, 2023 at 11:15 PM Kui Liu <Kui.Liu at acronis.com> wrote:
>
> Both size of qhash and limit of each bucket can affect performance of
>
> certain workload significantly. There is no single set of value that'd
>
> be the best for all workload, we may need to choose a value based on
>
> workload, so it'd be better make them configurable.
>
>
>
> Here we choose the default value to be 16 (qhash size) x 256 (bucket
>
> limit).
>
>
>
> Signed-off-by: Liu Kui <Kui.Liu at acronis.com>
>
> ---
>
> fs/fuse/dev.c    | 5 ++---
>
> fs/fuse/fuse_i.h | 6 ++++--
>
> fs/fuse/inode.c  | 8 ++++++++
>
> 3 files changed, 14 insertions(+), 5 deletions(-)
>
>
>
> diff --git a/fs/fuse/dev.c b/fs/fuse/dev.c
>
> index 0023acc35204..8d15f76e0aea 100644
>
> --- a/fs/fuse/dev.c
>
> +++ b/fs/fuse/dev.c
>
> @@ -367,7 +367,7 @@ void __fuse_request_end( struct fuse_req *req, bool flush_bg)
>
>
>
>                                bg = true;
>
>
>
> -                               if (atomic_dec_return(&fc->qhash[bkt].num_reqs) < ((2*fc->max_background) / FUSE_QHASH_SIZE)) {
>
> +                              if (atomic_dec_return(&fc->qhash[bkt].num_reqs) < fuse_qhash_bucket_len) {
>
>                                                if (waitqueue_active(&fc->qhash[bkt].waitq))
>
>                                                                wake_up(&fc->qhash[bkt].waitq);
>
>                                }
>
> @@ -629,8 +629,7 @@ static int fuse_request_queue_background(struct fuse_req *req)
>
>                                                __clear_bit(FR_BACKGROUND, &req->flags);
>
>                                                __set_bit(FR_NO_ACCT, &req->flags);
>
>                                                if (wait_event_killable_exclusive(fc->qhash[bkt].waitq,
>
> -                                                                                                                 (atomic_read(&fc->qhash[bkt].num_reqs) <
>
> -                                                                                                                  ((2 * fc->max_background) / FUSE_QHASH_SIZE) ||
>
> +                                                                                                                (atomic_read(&fc->qhash[bkt].num_reqs) < fuse_qhash_bucket_len ||
>
>                                                                                                                   !READ_ONCE(fc->connected) ||
>
>                                                                                                                   (ff && test_bit(FUSE_S_FAIL_IMMEDIATELY, &ff->ff_state)))))
>
>                                                                return -EIO;
>
> diff --git a/fs/fuse/fuse_i.h b/fs/fuse/fuse_i.h
>
> index 487e1125f7e7..1633db46c6ef 100644
>
> --- a/fs/fuse/fuse_i.h
>
> +++ b/fs/fuse/fuse_i.h
>
> @@ -642,7 +642,7 @@ struct fuse_kio_ops {
>
> int fuse_register_kio(struct fuse_kio_ops *ops);
>
> void fuse_unregister_kio(struct fuse_kio_ops *ops);
>
>
>
> -#define FUSE_QHASH_SIZE 64
>
> +#define FUSE_QHASH_SIZE 128
>
>
>
> #include <linux/jhash.h>
>
>
>
> @@ -659,9 +659,11 @@ static inline unsigned int fuse_qhash_bucket(struct fuse_args * args)
>
>                return jhash_2words(val & 0xFFFFFFFFU, val >> 32, 0) & (FUSE_QHASH_SIZE - 1);
>
> }
>
> #else
>
> +extern unsigned int fuse_qhash_size;
>
> +extern unsigned int fuse_qhash_bucket_len;
>
> static inline unsigned int fuse_qhash_bucket(void)
>
> {
>
> -               return jhash_1word(current->pid, 0) & (FUSE_QHASH_SIZE - 1);
>
> +              return jhash_1word(current->pid, 0) & (FUSE_QHASH_SIZE - 1) & (fuse_qhash_size - 1);
>
> }
>
> #endif
>
>
>
> diff --git a/fs/fuse/inode.c b/fs/fuse/inode.c
>
> index 33cd8f9944ca..49993e1d20a5 100644
>
> --- a/fs/fuse/inode.c
>
> +++ b/fs/fuse/inode.c
>
> @@ -54,6 +54,14 @@ MODULE_PARM_DESC(max_user_congthresh,
>
>   "Global limit for the maximum congestion threshold an "
>
>   "unprivileged user can set");
>
>
>
> +unsigned int fuse_qhash_size = 16;
>
> +module_param(fuse_qhash_size, uint, 0600);
>
> +MODULE_PARM_DESC(fuse_qhash_size, "Number of qhash buckets, must be power of 2");
>
> +
>
> +unsigned int fuse_qhash_bucket_len = 256;
>
> +module_param(fuse_qhash_bucket_len, uint, 0600);
>
> +MODULE_PARM_DESC(fuse_qhash_bucket_len, "Limit of a qhash bucket");
>
> +
>
> #define FUSE_SUPER_MAGIC 0x65735546
>
>
>
> #define FUSE_DEFAULT_BLKSIZE 512
>
> --
>
> 2.32.0 (Apple Git-132)
>
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