ping ? On 5/23/2023 2:48 PM, Hou Tao wrote: > ping ? > > On 5/8/2023 8:08 PM, Hou Tao wrote: >> ping ? >> >> On 4/28/2023 3:44 PM, Hou Tao wrote: >>> From: Hou Tao <houtao1@xxxxxxxxxx> >>> >>> Since commit a78418e6a04c ("block: Always initialize bio IO priority on >>> submit"), bio->bi_ioprio will never be IOPRIO_CLASS_NONE when calling >>> blkcg_set_ioprio(), so there will be no way to promote the io-priority >>> of one cgroup to IOPRIO_CLASS_RT, because bi_ioprio will always be >>> greater than or equals to IOPRIO_CLASS_RT. >>> >>> It seems possible to call blkcg_set_ioprio() first then try to >>> initialize bi_ioprio later in bio_set_ioprio(), but this doesn't work >>> for bio in which bi_ioprio is already initialized (e.g., direct-io), so >>> introduce a new promote-to-rt policy to promote the iopriority of bio to >>> IOPRIO_CLASS_RT if the ioprio is not already RT. >>> >>> For none-to-rt policy, although it doesn't work now, but considering >>> that its purpose was also to override the io-priority to RT and allowing >>> for a smoother transition, just keep it and treat it as an alias of >>> the promote-to-rt policy. >>> >>> Acked-by: Tejun Heo <tj@xxxxxxxxxx> >>> Reviewed-by: Bart Van Assche <bvanassche@xxxxxxx> >>> Reviewed-by: Chaitanya Kulkarni <kch@xxxxxxxxxx> >>> Reviewed-by: Jan Kara <jack@xxxxxxx> >>> Signed-off-by: Hou Tao <houtao1@xxxxxxxxxx> >>> --- >>> v4: >>> * rebased on 33afd4b76393 >>> * Add Reviewed-by from Jan Kara >>> >>> v3: https://lore.kernel.org/linux-block/20230223135154.3749088-1-houtao@xxxxxxxxxxxxxxx >>> * Use 'non-RT' instead of 'no-RT' in document (from Bagas) >>> * Remove repeated sentence in commit message >>> * Add Reviewed-by and Acked-by tags >>> >>> v2: https://lore.kernel.org/linux-block/20230220135428.2632906-1-houtao@xxxxxxxxxxxxxxx >>> >>> * Simplify the implementation of promote-to-rt (from Bart) >>> * Make none-to-rt to work again by treating it as an alias of >>> the promote-to-rt policy (from Bart & Jan) >>> * fix the style of new content in cgroup-v2.rst (from Bagas) >>> * set the default priority level to 4 instead of 0 for promote-to-rt >>> >>> v1: https://lore.kernel.org/linux-block/20230201045227.2203123-1-houtao@xxxxxxxxxxxxxxx >>> >>> Documentation/admin-guide/cgroup-v2.rst | 42 ++++++++++++++----------- >>> block/blk-ioprio.c | 23 ++++++++++++-- >>> 2 files changed, 44 insertions(+), 21 deletions(-) >>> >>> diff --git a/Documentation/admin-guide/cgroup-v2.rst b/Documentation/admin-guide/cgroup-v2.rst >>> index f67c0829350b..7544ce00e0cb 100644 >>> --- a/Documentation/admin-guide/cgroup-v2.rst >>> +++ b/Documentation/admin-guide/cgroup-v2.rst >>> @@ -2024,31 +2024,33 @@ that attribute: >>> no-change >>> Do not modify the I/O priority class. >>> >>> - none-to-rt >>> - For requests that do not have an I/O priority class (NONE), >>> - change the I/O priority class into RT. Do not modify >>> - the I/O priority class of other requests. >>> + promote-to-rt >>> + For requests that have a non-RT I/O priority class, change it into RT. >>> + Also change the priority level of these requests to 4. Do not modify >>> + the I/O priority of requests that have priority class RT. >>> >>> restrict-to-be >>> For requests that do not have an I/O priority class or that have I/O >>> - priority class RT, change it into BE. Do not modify the I/O priority >>> - class of requests that have priority class IDLE. >>> + priority class RT, change it into BE. Also change the priority level >>> + of these requests to 0. Do not modify the I/O priority class of >>> + requests that have priority class IDLE. >>> >>> idle >>> Change the I/O priority class of all requests into IDLE, the lowest >>> I/O priority class. >>> >>> + none-to-rt >>> + Deprecated. Just an alias for promote-to-rt. >>> + >>> The following numerical values are associated with the I/O priority policies: >>> >>> -+-------------+---+ >>> -| no-change | 0 | >>> -+-------------+---+ >>> -| none-to-rt | 1 | >>> -+-------------+---+ >>> -| rt-to-be | 2 | >>> -+-------------+---+ >>> -| all-to-idle | 3 | >>> -+-------------+---+ >>> ++----------------+---+ >>> +| no-change | 0 | >>> ++----------------+---+ >>> +| rt-to-be | 2 | >>> ++----------------+---+ >>> +| all-to-idle | 3 | >>> ++----------------+---+ >>> >>> The numerical value that corresponds to each I/O priority class is as follows: >>> >>> @@ -2064,9 +2066,13 @@ The numerical value that corresponds to each I/O priority class is as follows: >>> >>> The algorithm to set the I/O priority class for a request is as follows: >>> >>> -- Translate the I/O priority class policy into a number. >>> -- Change the request I/O priority class into the maximum of the I/O priority >>> - class policy number and the numerical I/O priority class. >>> +- If I/O priority class policy is promote-to-rt, change the request I/O >>> + priority class to IOPRIO_CLASS_RT and change the request I/O priority >>> + level to 4. >>> +- If I/O priorityt class is not promote-to-rt, translate the I/O priority >>> + class policy into a number, then change the request I/O priority class >>> + into the maximum of the I/O priority class policy number and the numerical >>> + I/O priority class. >>> >>> PID >>> --- >>> diff --git a/block/blk-ioprio.c b/block/blk-ioprio.c >>> index 055529b9b92b..4051fada01f1 100644 >>> --- a/block/blk-ioprio.c >>> +++ b/block/blk-ioprio.c >>> @@ -23,25 +23,28 @@ >>> /** >>> * enum prio_policy - I/O priority class policy. >>> * @POLICY_NO_CHANGE: (default) do not modify the I/O priority class. >>> - * @POLICY_NONE_TO_RT: modify IOPRIO_CLASS_NONE into IOPRIO_CLASS_RT. >>> + * @POLICY_PROMOTE_TO_RT: modify no-IOPRIO_CLASS_RT to IOPRIO_CLASS_RT. >>> * @POLICY_RESTRICT_TO_BE: modify IOPRIO_CLASS_NONE and IOPRIO_CLASS_RT into >>> * IOPRIO_CLASS_BE. >>> * @POLICY_ALL_TO_IDLE: change the I/O priority class into IOPRIO_CLASS_IDLE. >>> + * @POLICY_NONE_TO_RT: an alias for POLICY_PROMOTE_TO_RT. >>> * >>> * See also <linux/ioprio.h>. >>> */ >>> enum prio_policy { >>> POLICY_NO_CHANGE = 0, >>> - POLICY_NONE_TO_RT = 1, >>> + POLICY_PROMOTE_TO_RT = 1, >>> POLICY_RESTRICT_TO_BE = 2, >>> POLICY_ALL_TO_IDLE = 3, >>> + POLICY_NONE_TO_RT = 4, >>> }; >>> >>> static const char *policy_name[] = { >>> [POLICY_NO_CHANGE] = "no-change", >>> - [POLICY_NONE_TO_RT] = "none-to-rt", >>> + [POLICY_PROMOTE_TO_RT] = "promote-to-rt", >>> [POLICY_RESTRICT_TO_BE] = "restrict-to-be", >>> [POLICY_ALL_TO_IDLE] = "idle", >>> + [POLICY_NONE_TO_RT] = "none-to-rt", >>> }; >>> >>> static struct blkcg_policy ioprio_policy; >>> @@ -189,6 +192,20 @@ void blkcg_set_ioprio(struct bio *bio) >>> if (!blkcg || blkcg->prio_policy == POLICY_NO_CHANGE) >>> return; >>> >>> + if (blkcg->prio_policy == POLICY_PROMOTE_TO_RT || >>> + blkcg->prio_policy == POLICY_NONE_TO_RT) { >>> + /* >>> + * For RT threads, the default priority level is 4 because >>> + * task_nice is 0. By promoting non-RT io-priority to RT-class >>> + * and default level 4, those requests that are already >>> + * RT-class but need a higher io-priority can use ioprio_set() >>> + * to achieve this. >>> + */ >>> + if (IOPRIO_PRIO_CLASS(bio->bi_ioprio) != IOPRIO_CLASS_RT) >>> + bio->bi_ioprio = IOPRIO_PRIO_VALUE(IOPRIO_CLASS_RT, 4); >>> + return; >>> + } >>> + >>> /* >>> * Except for IOPRIO_CLASS_NONE, higher I/O priority numbers >>> * correspond to a lower priority. Hence, the max_t() below selects >> . > .