Bug 215485
| Summary: | mismatch between front_merges and async_depth tunable | ||
|---|---|---|---|
| Product: | IO/Storage | Reporter: | gzhqyz |
| Component: | Block Layer | Assignee: | Jens Axboe (axboe) |
| Status: | RESOLVED CODE_FIX | ||
| Severity: | normal | CC: | regressions |
| Priority: | P1 | ||
| Hardware: | All | ||
| OS: | Linux | ||
| Kernel Version: | 5.16 | Subsystem: | |
| Regression: | No | Bisected commit-id: | |
is this a regression? e.g., is there anything that works worse due to that change? BTW, bugzilla might be a bad place for this kind of thing, better report it my email, as outlined here: https://www.kernel.org/doc/html/latest/admin-guide/reporting-issues.html Thanks for reporting this! |
Hi, commit 0775758 ("block/mq-deadline: Reserve 25% of scheduler tags for synchronous requests") add async_depth parameter to mq-deadline. If I unstandard correctly, its value is stored to front_merges, see [1]. If I change async_depth, front_merges is also changed. I'm not pretty sure, but it seems like a mistake as front_merges should be a bool value[2]. [1] https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git/tree/block/mq-deadline.c?h=v5.16#n898 [2] https://www.kernel.org/doc/Documentation/block/deadline-iosched.txt # grep -R . /sys/block/*/queue/iosched/ /sys/block/sda/queue/iosched/front_merges:1 /sys/block/sda/queue/iosched/read_expire:200 /sys/block/sda/queue/iosched/prio_aging_expire:10000 /sys/block/sda/queue/iosched/fifo_batch:16 /sys/block/sda/queue/iosched/write_expire:5000 /sys/block/sda/queue/iosched/writes_starved:4 /sys/block/sda/queue/iosched/async_depth:1 # echo 1234 > /sys/block/sda/queue/iosched/async_depth # grep -R . /sys/block/*/queue/iosched/ /sys/block/sda/queue/iosched/front_merges:1234 /sys/block/sda/queue/iosched/read_expire:200 /sys/block/sda/queue/iosched/prio_aging_expire:10000 /sys/block/sda/queue/iosched/fifo_batch:16 /sys/block/sda/queue/iosched/write_expire:5000 /sys/block/sda/queue/iosched/writes_starved:4 /sys/block/sda/queue/iosched/async_depth:1234