With large number of tracked references list searches under the lock
become too expensive, creating enormous lock contention.
On my tests with ZFS_DEBUG enabled this increases write throughput
with 32KB blocks from ~1.2GB/s to ~7.5GB/s.
Reviewed-by: Brian Atkinson <batkinson@lanl.gov>
Reviewed-by: Brian Behlendorf <behlendorf1@llnl.gov>
Signed-off-by: Alexander Motin <mav@FreeBSD.org>
Sponsored by: iXsystems, Inc.
Closes#14970
There are two places where we need to add/remove several references
with semantics of zfs_refcount_(add|remove). But when debug/tracing
is disabled, it is a crime to run multiple atomic_inc() in a loop,
especially under congested pool-wide allocator lock.
Introduced new functions implement the same semantics as the loop,
but without overhead in production builds.
Reviewed-by: Rich Ercolani <rincebrain@gmail.com>
Reviewed-by: Brian Behlendorf <behlendorf1@llnl.gov>
Signed-off-by: Alexander Motin <mav@FreeBSD.org>
Sponsored by: iXsystems, Inc.
Closes#14934
refcount_add_many(foo,N) is not the same as
for (i=0; i < N; i++) { refcount_add(foo); }
Unfortunately, this is only actually true with debug kernels and
reference_tracking_enable=1.
Reviewed-by: Brian Behlendorf <behlendorf1@llnl.gov>
Signed-off-by: Rich Ercolani <rincebrain@gmail.com>
Closes#12589Closes#12602
Use atomic_load_64() for zfs_refcount_count() to prevent torn reads
on 32-bit platforms. On 64-bit ones it should not change anything.
When built with ZFS_DEBUG but running without tracking enabled use
atomics instead of mutexes same as for builds without ZFS_DEBUG.
Since rc_tracked can't change live we can check it without lock.
Reviewed-by: Brian Behlendorf <behlendorf1@llnl.gov>
Reviewed-by: Matthew Ahrens <mahrens@delphix.com>
Signed-off-by: Alexander Motin <mav@FreeBSD.org>
Sponsored-By: iXsystems, Inc.
Closes#12420
Renamed to avoid conflicting with refcount.h when a different
implementation is already provided by the platform.
Reviewed-by: Ryan Moeller <ryan@ixsystems.com>
Reviewed-by: Brian Behlendorf <behlendorf1@llnl.gov>
Signed-off-by: Matt Macy <mmacy@FreeBSD.org>
Closes#10620
Alexander Motin
Tino Reichardt
Rich Ercolani
Matthew Macy