fix #5014 reenable blk-mq optimization
While I think the huge performance optimization was at some point not really that huge in practice - the feature sounds like it would benefit our use-case: https://github.com/openzfs/zfs/pull/13148 currently the feature is disabled in 2.2.0 (see the second patch), because of the issues addressed by the first patch Signed-off-by: Stoiko Ivanov <s.ivanov@proxmox.com> Signed-off-by: Thomas Lamprecht <t.lamprecht@proxmox.com>
This commit is contained in:
Stoiko Ivanov
Thomas Lamprecht
parent
28de0abfa9
commit
7e3b7d81a1
99
debian/patches/0010-zvol-Remove-broken-blk-mq-optimization.patch
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99
debian/patches/0010-zvol-Remove-broken-blk-mq-optimization.patch
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@ -0,0 +1,99 @@
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From 0000000000000000000000000000000000000000 Mon Sep 17 00:00:00 2001
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From: Tony Hutter <hutter2@llnl.gov>
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Date: Mon, 23 Oct 2023 14:45:06 -0700
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Subject: [PATCH] zvol: Remove broken blk-mq optimization
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This fix removes a dubious optimization in zfs_uiomove_bvec_rq()
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that saved the iterator contents of a rq_for_each_segment(). This
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optimization allowed restoring the "saved state" from a previous
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rq_for_each_segment() call on the same uio so that you wouldn't
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need to iterate though each bvec on every zfs_uiomove_bvec_rq() call.
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However, if the kernel is manipulating the requests/bios/bvecs under
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the covers between zfs_uiomove_bvec_rq() calls, then it could result
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in corruption from using the "saved state". This optimization
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results in an unbootable system after installing an OS on a zvol
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with blk-mq enabled.
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Reviewed-by: Brian Behlendorf <behlendorf1@llnl.gov>
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Signed-off-by: Tony Hutter <hutter2@llnl.gov>
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Closes #15351
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(cherry picked from commit 7c9b6fed16ed5034fd1cdfdaedfad93dc97b1557)
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Signed-off-by: Stoiko Ivanov <s.ivanov@proxmox.com>
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---
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include/os/linux/spl/sys/uio.h | 8 --------
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module/os/linux/zfs/zfs_uio.c | 29 -----------------------------
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2 files changed, 37 deletions(-)
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diff --git a/include/os/linux/spl/sys/uio.h b/include/os/linux/spl/sys/uio.h
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index cce097e16..a4b600004 100644
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--- a/include/os/linux/spl/sys/uio.h
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+++ b/include/os/linux/spl/sys/uio.h
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@@ -73,13 +73,6 @@ typedef struct zfs_uio {
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size_t uio_skip;
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struct request *rq;
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-
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- /*
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- * Used for saving rq_for_each_segment() state between calls
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- * to zfs_uiomove_bvec_rq().
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- */
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- struct req_iterator iter;
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- struct bio_vec bv;
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} zfs_uio_t;
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@@ -138,7 +131,6 @@ zfs_uio_bvec_init(zfs_uio_t *uio, struct bio *bio, struct request *rq)
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} else {
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uio->uio_bvec = NULL;
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uio->uio_iovcnt = 0;
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- memset(&uio->iter, 0, sizeof (uio->iter));
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}
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uio->uio_loffset = io_offset(bio, rq);
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diff --git a/module/os/linux/zfs/zfs_uio.c b/module/os/linux/zfs/zfs_uio.c
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index 3efd4ab15..c2ed67c43 100644
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--- a/module/os/linux/zfs/zfs_uio.c
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+++ b/module/os/linux/zfs/zfs_uio.c
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@@ -204,22 +204,6 @@ zfs_uiomove_bvec_rq(void *p, size_t n, zfs_uio_rw_t rw, zfs_uio_t *uio)
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this_seg_start = orig_loffset;
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rq_for_each_segment(bv, rq, iter) {
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- if (uio->iter.bio) {
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- /*
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- * If uio->iter.bio is present, then we know we've saved
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- * uio->iter from a previous call to this function, and
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- * we can skip ahead in this rq_for_each_segment() loop
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- * to where we last left off. That way, we don't need
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- * to iterate over tons of segments we've already
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- * processed - we can just restore the "saved state".
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- */
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- iter = uio->iter;
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- bv = uio->bv;
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- this_seg_start = uio->uio_loffset;
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- memset(&uio->iter, 0, sizeof (uio->iter));
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- continue;
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- }
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-
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/*
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* Lookup what the logical offset of the last byte of this
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* segment is.
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@@ -260,19 +244,6 @@ zfs_uiomove_bvec_rq(void *p, size_t n, zfs_uio_rw_t rw, zfs_uio_t *uio)
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copied = 1; /* We copied some data */
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}
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- if (n == 0) {
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- /*
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- * All done copying. Save our 'iter' value to the uio.
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- * This allows us to "save our state" and skip ahead in
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- * the rq_for_each_segment() loop the next time we call
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- * call zfs_uiomove_bvec_rq() on this uio (which we
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- * will be doing for any remaining data in the uio).
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- */
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- uio->iter = iter; /* make a copy of the struct data */
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- uio->bv = bv;
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- return (0);
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- }
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-
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this_seg_start = this_seg_end + 1;
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}
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123
debian/patches/0011-Revert-zvol-Temporally-disable-blk-mq.patch
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123
debian/patches/0011-Revert-zvol-Temporally-disable-blk-mq.patch
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@ -0,0 +1,123 @@
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From 0000000000000000000000000000000000000000 Mon Sep 17 00:00:00 2001
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From: Tony Hutter <hutter2@llnl.gov>
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Date: Mon, 23 Oct 2023 14:39:59 -0700
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Subject: [PATCH] Revert "zvol: Temporally disable blk-mq"
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This reverts commit aefb6a2bd6c24597cde655e9ce69edd0a4c34357.
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aefb6a2bd temporally disabled blk-mq until we could fix a fix for
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Signed-off-by: Tony Hutter <hutter2@llnl.gov>
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Closes #15439
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(cherry picked from commit 05c4710e8958832afc2868102c9535a4f18115be)
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Signed-off-by: Stoiko Ivanov <s.ivanov@proxmox.com>
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---
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man/man4/zfs.4 | 57 ++++++++++++++++++++++++++++
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module/os/linux/zfs/zvol_os.c | 12 ++++++
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tests/zfs-tests/include/tunables.cfg | 2 +-
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3 files changed, 70 insertions(+), 1 deletion(-)
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diff --git a/man/man4/zfs.4 b/man/man4/zfs.4
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index 71a3e67ee..cfadd79d8 100644
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--- a/man/man4/zfs.4
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+++ b/man/man4/zfs.4
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@@ -2317,6 +2317,63 @@ If
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.Sy zvol_threads
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to the number of CPUs present or 32 (whichever is greater).
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.
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+.It Sy zvol_blk_mq_threads Ns = Ns Sy 0 Pq uint
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+The number of threads per zvol to use for queuing IO requests.
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+This parameter will only appear if your kernel supports
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+.Li blk-mq
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+and is only read and assigned to a zvol at zvol load time.
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+If
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+.Sy 0
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+(the default) then internally set
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+.Sy zvol_blk_mq_threads
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+to the number of CPUs present.
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+.
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+.It Sy zvol_use_blk_mq Ns = Ns Sy 0 Ns | Ns 1 Pq uint
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+Set to
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+.Sy 1
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+to use the
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+.Li blk-mq
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+API for zvols.
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+Set to
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+.Sy 0
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+(the default) to use the legacy zvol APIs.
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+This setting can give better or worse zvol performance depending on
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+the workload.
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+This parameter will only appear if your kernel supports
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+.Li blk-mq
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+and is only read and assigned to a zvol at zvol load time.
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+.
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+.It Sy zvol_blk_mq_blocks_per_thread Ns = Ns Sy 8 Pq uint
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+If
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+.Sy zvol_use_blk_mq
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+is enabled, then process this number of
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+.Sy volblocksize Ns -sized blocks per zvol thread.
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+This tunable can be use to favor better performance for zvol reads (lower
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+values) or writes (higher values).
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+If set to
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+.Sy 0 ,
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+then the zvol layer will process the maximum number of blocks
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+per thread that it can.
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+This parameter will only appear if your kernel supports
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+.Li blk-mq
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+and is only applied at each zvol's load time.
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+.
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+.It Sy zvol_blk_mq_queue_depth Ns = Ns Sy 0 Pq uint
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+The queue_depth value for the zvol
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+.Li blk-mq
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+interface.
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+This parameter will only appear if your kernel supports
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+.Li blk-mq
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+and is only applied at each zvol's load time.
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+If
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+.Sy 0
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+(the default) then use the kernel's default queue depth.
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+Values are clamped to the kernel's
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+.Dv BLKDEV_MIN_RQ
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+and
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+.Dv BLKDEV_MAX_RQ Ns / Ns Dv BLKDEV_DEFAULT_RQ
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+limits.
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+.
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.It Sy zvol_volmode Ns = Ns Sy 1 Pq uint
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Defines zvol block devices behaviour when
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.Sy volmode Ns = Ns Sy default :
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diff --git a/module/os/linux/zfs/zvol_os.c b/module/os/linux/zfs/zvol_os.c
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index 76521c959..7a95b54bd 100644
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--- a/module/os/linux/zfs/zvol_os.c
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+++ b/module/os/linux/zfs/zvol_os.c
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@@ -1620,6 +1620,18 @@ MODULE_PARM_DESC(zvol_prefetch_bytes, "Prefetch N bytes at zvol start+end");
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module_param(zvol_volmode, uint, 0644);
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MODULE_PARM_DESC(zvol_volmode, "Default volmode property value");
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+#ifdef HAVE_BLK_MQ
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+module_param(zvol_blk_mq_queue_depth, uint, 0644);
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+MODULE_PARM_DESC(zvol_blk_mq_queue_depth, "Default blk-mq queue depth");
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+
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+module_param(zvol_use_blk_mq, uint, 0644);
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+MODULE_PARM_DESC(zvol_use_blk_mq, "Use the blk-mq API for zvols");
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+
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+module_param(zvol_blk_mq_blocks_per_thread, uint, 0644);
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+MODULE_PARM_DESC(zvol_blk_mq_blocks_per_thread,
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+ "Process volblocksize blocks per thread");
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+#endif
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+
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#ifndef HAVE_BLKDEV_GET_ERESTARTSYS
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module_param(zvol_open_timeout_ms, uint, 0644);
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MODULE_PARM_DESC(zvol_open_timeout_ms, "Timeout for ZVOL open retries");
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diff --git a/tests/zfs-tests/include/tunables.cfg b/tests/zfs-tests/include/tunables.cfg
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index 8010a9451..80e7bcb3b 100644
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--- a/tests/zfs-tests/include/tunables.cfg
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+++ b/tests/zfs-tests/include/tunables.cfg
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@@ -89,7 +89,7 @@ VDEV_VALIDATE_SKIP vdev.validate_skip vdev_validate_skip
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VOL_INHIBIT_DEV UNSUPPORTED zvol_inhibit_dev
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VOL_MODE vol.mode zvol_volmode
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VOL_RECURSIVE vol.recursive UNSUPPORTED
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-VOL_USE_BLK_MQ UNSUPPORTED UNSUPPORTED
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+VOL_USE_BLK_MQ UNSUPPORTED zvol_use_blk_mq
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XATTR_COMPAT xattr_compat zfs_xattr_compat
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ZEVENT_LEN_MAX zevent.len_max zfs_zevent_len_max
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ZEVENT_RETAIN_MAX zevent.retain_max zfs_zevent_retain_max
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2
debian/patches/series
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2
debian/patches/series
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@ -7,3 +7,5 @@
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0007-Add-systemd-unit-for-importing-specific-pools.patch
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0008-Patch-move-manpage-arcstat-1-to-arcstat-8.patch
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0009-arc-stat-summary-guard-access-to-l2arc-MFU-MRU-stats.patch
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0010-zvol-Remove-broken-blk-mq-optimization.patch
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0011-Revert-zvol-Temporally-disable-blk-mq.patch
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