The commit is pushed to "branch-rh8-4.18.0-80.1.2.vz8.2.x-ovz" and will appear
at https://src.openvz.org/scm/ovz/vzkernel.git
after rh8-4.18.0-80.1.2.vz8.3.1
------>
commit a78e75c3a099c2555467448c981a86c5129c82c1
Author: Angelo Ruocco <angeloruocc...@gmail.com>
Date: Wed Jan 29 12:16:55 2020 +0000
ms/block, bfq: add weight symlink to the bfq.weight cgroup parameter
Many userspace tools and services use the proportional-share policy of
the blkio/io cgroups controller. The CFQ I/O scheduler implemented
this policy for the legacy block layer. To modify the weight of a
group in case CFQ was in charge, the 'weight' parameter of the group
must be modified. On the other hand, the BFQ I/O scheduler implements
the same policy in blk-mq, but, with BFQ, the parameter to modify has
a different name: bfq.weight (forced choice until legacy block was
present, because two different policies cannot share a common parameter
in cgroups).
Due to CFQ legacy, most if not all userspace configurations still use
the parameter 'weight', and for the moment do not seem likely to be
changed. But, when CFQ went away with legacy block, such a parameter
ceased to exist.
So, a simple workaround has been proposed [1] to make all
configurations work: add a symlink, named weight, to bfq.weight. This
commit adds such a symlink.
[1] https://lkml.org/lkml/2019/4/8/555
Suggested-by: Johannes Thumshirn <jthumsh...@suse.de>
Signed-off-by: Angelo Ruocco <angeloruocc...@gmail.com>
Signed-off-by: Paolo Valente <paolo.vale...@linaro.org>
Signed-off-by: Jens Axboe <ax...@kernel.dk>
(cherry-picked from 19e9da9e86c43687ed6a56bd39a52c6649973a35)
https://jira.sw.ru/browse/PSBM-101019
Signed-off-by: Andrey Ryabinin <aryabi...@virtuozzo.com>
---
block/bfq-cgroup.c | 6 ++++--
1 file changed, 4 insertions(+), 2 deletions(-)
diff --git a/block/bfq-cgroup.c b/block/bfq-cgroup.c
index c6113af..27f158f 100644
--- a/block/bfq-cgroup.c
+++ b/block/bfq-cgroup.c
@@ -1054,7 +1054,8 @@ struct blkcg_policy blkcg_policy_bfq = {
struct cftype bfq_blkcg_legacy_files[] = {
{
.name = "bfq.weight",
- .flags = CFTYPE_NOT_ON_ROOT,
+ .link_name = "weight",
+ .flags = CFTYPE_NOT_ON_ROOT | CFTYPE_SYMLINKED,
.seq_show = bfq_io_show_weight,
.write_u64 = bfq_io_set_weight_legacy,
},
@@ -1174,7 +1175,8 @@ struct cftype bfq_blkcg_legacy_files[] = {
struct cftype bfq_blkg_files[] = {
{
.name = "bfq.weight",
- .flags = CFTYPE_NOT_ON_ROOT,
+ .link_name = "weight",
+ .flags = CFTYPE_NOT_ON_ROOT | CFTYPE_SYMLINKED,
.seq_show = bfq_io_show_weight,
.write = bfq_io_set_weight,
},
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