Messages in this thread | | | From | Chaitanya Kulkarni <> | Subject | [PATCH V2 0/3] block: set ioprio value | Date | Tue, 20 Aug 2019 23:11:53 -0700 |
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Hi,
While experimenting with the ionice, I came across the scenario where I cannot see the bio/request priority field being set when using blkdiscard for REQ_OP_DISCARD, REQ_OP_WRITE_ZEROES and other operations like REQ_OP_WRITE_SAME, REQ_OP_ZONE_RESET, and flush.
This is a small patch-series which sets the ioprio value at various places for the zone-reset, flush, write-zeroes and discard operations. This patch series uses get_current_ioprio() so that bio associated with the respective operation can inherit the value from current process.
In order to test this, I've modified the null_blk and enabled the write_zeroes through module param. Following are the results.
Without these patches:-
# modprobe null_blk gb=5 nr_devices=1 write_zeroes=1 # for prio in `seq 0 3`; do ionice -c ${prio} blkdiscard -z -o 0 -l 4096 /dev/nullb0; done # dmesg -c [ 402.958458] null_handle_cmd REQ_OP_WRITE_ZEROES priority class 0 [ 402.966024] null_handle_cmd REQ_OP_WRITE_ZEROES priority class 0 [ 402.973960] null_handle_cmd REQ_OP_WRITE_ZEROES priority class 0 [ 402.981373] null_handle_cmd REQ_OP_WRITE_ZEROES priority class 0 #
With these patches:-
# modprobe null_blk gb=5 nr_devices=1 write_zeroes=1 # for prio in `seq 0 3`; do ionice -c ${prio} blkdiscard -z -o 0 -l 4096 /dev/nullb0; done # dmesg -c [ 1426.091772] null_handle_cmd REQ_OP_WRITE_ZEROES priority class 0 [ 1426.100177] null_handle_cmd REQ_OP_WRITE_ZEROES priority class 1 [ 1426.108035] null_handle_cmd REQ_OP_WRITE_ZEROES priority class 2 [ 1426.115768] null_handle_cmd REQ_OP_WRITE_ZEROES priority class 3 #
With the block trace extension support is being worked on [1] which has the ability to report the I/O priority, now we can track the correct priority values with this patch-series.
Regards, Chaitanya
[1] https://www.spinics.net/lists/linux-btrace/msg00880.html
* Changes from V1:- 1. Adjust the code for new changes from linux-block/for-next.
Chaitanya Kulkarni (3): block: set ioprio for zone-reset bio block: set ioprio for flush bio block: set ioprio for discard, write-zeroes etc
block/blk-flush.c | 1 + block/blk-lib.c | 4 ++++ block/blk-zoned.c | 2 ++ 3 files changed, 7 insertions(+)
-- 2.17.0
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