[2.2] zvol: use multiple taskqs #16098
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Currently, zvol uses a single taskq, resulting in throughput bottleneck
under heavy load due to lock contention on the single taskq. This patch
addresses the performance bottleneck under heavy load conditions by
utilizing multiple taskqs, thus mitigating lock contention. The number
of taskqs scale dynamically based on the available CPUs in the system,
as illustrated below:
taskq total
cpus taskqs threads threads
------- ------- ------- -------
1 1 32 32
2 1 32 32
4 1 32 32
8 2 16 32
16 3 11 33
32 5 7 35
64 8 8 64
128 11 12 132
256 16 16 256
Reviewed-by: Alexander Motin <[email protected]>
Reviewed-by: Tony Hutter <[email protected]>
Reviewed-by: Brian Behlendorf <[email protected]>
Reviewed-by: Tony Nguyen <[email protected]>
Signed-off-by: Ameer Hamza <[email protected]>
Closes openzfs#15992
99741bd introduced zvol_num_taskqs, but put it behind the HAVE_BLK_MQ define, preventing builds on versions of Linux that don't have it (<3.13, incl EL7). Nothing about it seems dependent on blk-mq, so this just moves it out from behind that define and so fixes the build. Sponsored-by: Klara, Inc. Sponsored-by: Wasabi Technology, Inc. Reviewed-by: Ameer Hamza <[email protected]> Reviewed-by: Alexander Motin <[email protected]> Reviewed-by: Brian Behlendorf <[email protected]> Signed-off-by: Rob Norris <[email protected]> Closes openzfs#16062
99741bd accesses a cached blk-mq hardware context through the mq_hctx field of struct request. However, this field did not exist until 5.0. Before that, the private function blk_mq_map_queue() was used to dig it out of broader queue context. This commit detects this situation, and handles it with a poor-man's simulation of that function. Sponsored-by: Klara, Inc. Sponsored-by: Wasabi Technology, Inc. Reviewed-by: Ameer Hamza <[email protected]> Reviewed-by: Alexander Motin <[email protected]> Reviewed-by: Brian Behlendorf <[email protected]> Signed-off-by: Rob Norris <[email protected]> Closes openzfs#16069
amotin
approved these changes
Apr 16, 2024
tonyhutter
approved these changes
Apr 16, 2024
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Motivation and Context
Backport #15992 along with c13400c and 03987f7.
Description
See #15992.
How Has This Been Tested?
CI Testing.
Types of changes
Checklist:
Signed-off-by.