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Message-ID: <4D8873DD.80800@cn.fujitsu.com>
Date: Tue, 22 Mar 2011 18:03:09 +0800
From: Gui Jianfeng <guijianfeng@...fujitsu.com>
To: Chad Talbott <ctalbott@...gle.com>
CC: jaxboe@...ionio.com, vgoyal@...hat.com,
linux-kernel@...r.kernel.org, mrubin@...gle.com,
teravest@...gle.com
Subject: Re: [PATCH 1/3] cfq-iosched: Fair cross-group preemption (interface
and documentation)
Chad Talbott wrote:
> blkio.class is a new interface that allows you to specify a cgroup as
> requiring low-latency service on a specific block device. This patch
> includes only the interface and documentation.
>
> Signed-off-by: Chad Talbott <ctalbott@...gle.com>
> ---
> Documentation/cgroups/blkio-controller.txt | 16 ++++
> block/blk-cgroup.c | 121 +++++++++++++++++++++-------
> block/blk-cgroup.h | 36 +++++++--
> block/cfq-iosched.c | 12 +++-
> 4 files changed, 145 insertions(+), 40 deletions(-)
>
> diff --git a/Documentation/cgroups/blkio-controller.txt b/Documentation/cgroups/blkio-controller.txt
> index 4ed7b5c..7acf9d2 100644
> --- a/Documentation/cgroups/blkio-controller.txt
> +++ b/Documentation/cgroups/blkio-controller.txt
> @@ -169,6 +169,22 @@ Proportional weight policy files
> dev weight
> 8:16 300
>
> +- blkio.class
> + - Specifies the per-cgroup, per-device service class. There
Hi Chad,
Do we need to implement a globle blkio.class interface as well as
a device specific one something like "blkio.class_device"? So a user
doesn't need to check every device number if he want to specify a
global value.
Thanks,
Gui
> + are currently two service classes: real-time (1) and
> + best-effort (2). By default, all groups start as
> + best-effort.
> +
> + #echo dev_maj:dev_minor class > /path/to/cgroup/blkio.class
> + Configure class=real-time on /dev/sdb (8:16) in this cgroup
> + # echo '8:16 1' > blkio.class
> + # cat blkio.class
> + 8:16 1
> +
> + A real-time group can preempt a best-effort group, only as
> + long as it's within its assigned weight; i.e. fairness is
> + preserved.
> +
> - blkio.time
> - disk time allocated to cgroup per device in milliseconds. First
> two fields specify the major and minor number of the device and
> diff --git a/block/blk-cgroup.c b/block/blk-cgroup.c
> index 455768a..f2c553e 100644
> --- a/block/blk-cgroup.c
> +++ b/block/blk-cgroup.c
> @@ -129,6 +129,21 @@ blkio_update_group_weight(struct blkio_group *blkg, unsigned int weight)
> }
> }
>
> +static inline void
> +blkio_update_group_class(struct blkio_group *blkg, unsigned int class)
> +{
> + struct blkio_policy_type *blkiop;
> +
> + list_for_each_entry(blkiop, &blkio_list, list) {
> + /* If this policy does not own the blkg, do not send updates */
> + if (blkiop->plid != blkg->plid)
> + continue;
> + if (blkiop->ops.blkio_update_group_class_fn)
> + blkiop->ops.blkio_update_group_class_fn(blkg->key,
> + blkg, class);
> + }
> +}
> +
> static inline void blkio_update_group_bps(struct blkio_group *blkg, u64 bps,
> int fileid)
> {
> @@ -708,15 +723,29 @@ static int blkio_policy_parse_and_set(char *buf,
>
> switch (plid) {
> case BLKIO_POLICY_PROP:
> - ret = strict_strtoul(s[1], 10, &temp);
> - if (ret || (temp < BLKIO_WEIGHT_MIN && temp > 0) ||
> - temp > BLKIO_WEIGHT_MAX)
> - return -EINVAL;
> -
> - newpn->plid = plid;
> - newpn->fileid = fileid;
> - newpn->val.weight = temp;
> - break;
> + switch (fileid) {
> + case BLKIO_PROP_weight_device:
> + ret = strict_strtoul(s[1], 10, &temp);
> + if (ret || (temp < BLKIO_WEIGHT_MIN && temp > 0) ||
> + temp > BLKIO_WEIGHT_MAX)
> + return -EINVAL;
> +
> + newpn->plid = plid;
> + newpn->fileid = fileid;
> + newpn->val.prop.weight = temp;
> + break;
> + case BLKIO_PROP_class:
> + ret = strict_strtoul(s[1], 10, &temp);
> + if (ret ||
> + temp < BLKIO_RT_CLASS ||
> + temp > BLKIO_BE_CLASS)
> + return -EINVAL;
> +
> + newpn->plid = plid;
> + newpn->fileid = fileid;
> + newpn->val.prop.class = temp;
> + break;
> + }
> case BLKIO_POLICY_THROTL:
> switch(fileid) {
> case BLKIO_THROTL_read_bps_device:
> @@ -727,7 +756,7 @@ static int blkio_policy_parse_and_set(char *buf,
>
> newpn->plid = plid;
> newpn->fileid = fileid;
> - newpn->val.bps = bps;
> + newpn->val.throtl.bps = bps;
> break;
> case BLKIO_THROTL_read_iops_device:
> case BLKIO_THROTL_write_iops_device:
> @@ -740,7 +769,7 @@ static int blkio_policy_parse_and_set(char *buf,
>
> newpn->plid = plid;
> newpn->fileid = fileid;
> - newpn->val.iops = (unsigned int)iops;
> + newpn->val.throtl.iops = (unsigned int)iops;
> break;
> }
> break;
> @@ -759,20 +788,34 @@ unsigned int blkcg_get_weight(struct blkio_cgroup *blkcg,
> pn = blkio_policy_search_node(blkcg, dev, BLKIO_POLICY_PROP,
> BLKIO_PROP_weight_device);
> if (pn)
> - return pn->val.weight;
> + return pn->val.prop.weight;
> else
> return blkcg->weight;
> }
> EXPORT_SYMBOL_GPL(blkcg_get_weight);
>
> -uint64_t blkcg_get_read_bps(struct blkio_cgroup *blkcg, dev_t dev)
> +enum blkcg_class blkcg_get_class(struct blkio_cgroup *blkcg,
> + dev_t dev)
> {
> struct blkio_policy_node *pn;
> + enum blkcg_class class = BLKIO_DEFAULT_CLASS;
> +
> + pn = blkio_policy_search_node(blkcg, dev, BLKIO_POLICY_PROP,
> + BLKIO_PROP_class);
> + if (pn)
> + class = pn->val.prop.class;
>
> + return class;
> +}
> +EXPORT_SYMBOL_GPL(blkcg_get_class);
> +
> +uint64_t blkcg_get_read_bps(struct blkio_cgroup *blkcg, dev_t dev)
> +{
> + struct blkio_policy_node *pn;
> pn = blkio_policy_search_node(blkcg, dev, BLKIO_POLICY_THROTL,
> BLKIO_THROTL_read_bps_device);
> if (pn)
> - return pn->val.bps;
> + return pn->val.throtl.bps;
> else
> return -1;
> }
> @@ -783,7 +826,7 @@ uint64_t blkcg_get_write_bps(struct blkio_cgroup *blkcg, dev_t dev)
> pn = blkio_policy_search_node(blkcg, dev, BLKIO_POLICY_THROTL,
> BLKIO_THROTL_write_bps_device);
> if (pn)
> - return pn->val.bps;
> + return pn->val.throtl.bps;
> else
> return -1;
> }
> @@ -795,7 +838,7 @@ unsigned int blkcg_get_read_iops(struct blkio_cgroup *blkcg, dev_t dev)
> pn = blkio_policy_search_node(blkcg, dev, BLKIO_POLICY_THROTL,
> BLKIO_THROTL_read_iops_device);
> if (pn)
> - return pn->val.iops;
> + return pn->val.throtl.iops;
> else
> return -1;
> }
> @@ -806,7 +849,7 @@ unsigned int blkcg_get_write_iops(struct blkio_cgroup *blkcg, dev_t dev)
> pn = blkio_policy_search_node(blkcg, dev, BLKIO_POLICY_THROTL,
> BLKIO_THROTL_write_iops_device);
> if (pn)
> - return pn->val.iops;
> + return pn->val.throtl.iops;
> else
> return -1;
> }
> @@ -816,19 +859,19 @@ static bool blkio_delete_rule_command(struct blkio_policy_node *pn)
> {
> switch(pn->plid) {
> case BLKIO_POLICY_PROP:
> - if (pn->val.weight == 0)
> + if (pn->val.prop.weight == 0)
> return 1;
> break;
> case BLKIO_POLICY_THROTL:
> switch(pn->fileid) {
> case BLKIO_THROTL_read_bps_device:
> case BLKIO_THROTL_write_bps_device:
> - if (pn->val.bps == 0)
> + if (pn->val.throtl.bps == 0)
> return 1;
> break;
> case BLKIO_THROTL_read_iops_device:
> case BLKIO_THROTL_write_iops_device:
> - if (pn->val.iops == 0)
> + if (pn->val.throtl.iops == 0)
> return 1;
> }
> break;
> @@ -844,17 +887,17 @@ static void blkio_update_policy_rule(struct blkio_policy_node *oldpn,
> {
> switch(oldpn->plid) {
> case BLKIO_POLICY_PROP:
> - oldpn->val.weight = newpn->val.weight;
> + oldpn->val.prop.weight = newpn->val.prop.weight;
> break;
> case BLKIO_POLICY_THROTL:
> switch(newpn->fileid) {
> case BLKIO_THROTL_read_bps_device:
> case BLKIO_THROTL_write_bps_device:
> - oldpn->val.bps = newpn->val.bps;
> + oldpn->val.throtl.bps = newpn->val.throtl.bps;
> break;
> case BLKIO_THROTL_read_iops_device:
> case BLKIO_THROTL_write_iops_device:
> - oldpn->val.iops = newpn->val.iops;
> + oldpn->val.throtl.iops = newpn->val.throtl.iops;
> }
> break;
> default:
> @@ -872,22 +915,24 @@ static void blkio_update_blkg_policy(struct blkio_cgroup *blkcg,
> unsigned int weight, iops;
> u64 bps;
>
> +
> switch(pn->plid) {
> case BLKIO_POLICY_PROP:
> - weight = pn->val.weight ? pn->val.weight :
> + weight = pn->val.prop.weight ? pn->val.prop.weight :
> blkcg->weight;
> blkio_update_group_weight(blkg, weight);
> + blkio_update_group_class(blkg, pn->val.prop.class);
> break;
> case BLKIO_POLICY_THROTL:
> switch(pn->fileid) {
> case BLKIO_THROTL_read_bps_device:
> case BLKIO_THROTL_write_bps_device:
> - bps = pn->val.bps ? pn->val.bps : (-1);
> + bps = pn->val.throtl.bps ? pn->val.throtl.bps : (-1);
> blkio_update_group_bps(blkg, bps, pn->fileid);
> break;
> case BLKIO_THROTL_read_iops_device:
> case BLKIO_THROTL_write_iops_device:
> - iops = pn->val.iops ? pn->val.iops : (-1);
> + iops = pn->val.throtl.iops ? pn->val.throtl.iops : (-1);
> blkio_update_group_iops(blkg, iops, pn->fileid);
> break;
> }
> @@ -984,21 +1029,28 @@ blkio_print_policy_node(struct seq_file *m, struct blkio_policy_node *pn)
> {
> switch(pn->plid) {
> case BLKIO_POLICY_PROP:
> - if (pn->fileid == BLKIO_PROP_weight_device)
> + switch(pn->fileid) {
> + case BLKIO_PROP_weight_device:
> + seq_printf(m, "%u:%u\t%u\n", MAJOR(pn->dev),
> + MINOR(pn->dev), pn->val.prop.weight);
> + break;
> + case BLKIO_PROP_class:
> seq_printf(m, "%u:%u\t%u\n", MAJOR(pn->dev),
> - MINOR(pn->dev), pn->val.weight);
> + MINOR(pn->dev), pn->val.prop.class);
> + break;
> + };
> break;
> case BLKIO_POLICY_THROTL:
> switch(pn->fileid) {
> case BLKIO_THROTL_read_bps_device:
> case BLKIO_THROTL_write_bps_device:
> seq_printf(m, "%u:%u\t%llu\n", MAJOR(pn->dev),
> - MINOR(pn->dev), pn->val.bps);
> + MINOR(pn->dev), pn->val.throtl.bps);
> break;
> case BLKIO_THROTL_read_iops_device:
> case BLKIO_THROTL_write_iops_device:
> seq_printf(m, "%u:%u\t%u\n", MAJOR(pn->dev),
> - MINOR(pn->dev), pn->val.iops);
> + MINOR(pn->dev), pn->val.throtl.iops);
> break;
> }
> break;
> @@ -1037,6 +1089,7 @@ static int blkiocg_file_read(struct cgroup *cgrp, struct cftype *cft,
> case BLKIO_POLICY_PROP:
> switch(name) {
> case BLKIO_PROP_weight_device:
> + case BLKIO_PROP_class:
> blkio_read_policy_node_files(cft, blkcg, m);
> return 0;
> default:
> @@ -1243,6 +1296,14 @@ struct cftype blkio_files[] = {
> .max_write_len = 256,
> },
> {
> + .name = "class",
> + .private = BLKIOFILE_PRIVATE(BLKIO_POLICY_PROP,
> + BLKIO_PROP_class),
> + .read_seq_string = blkiocg_file_read,
> + .write_string = blkiocg_file_write,
> + .max_write_len = 256,
> + },
> + {
> .name = "weight",
> .private = BLKIOFILE_PRIVATE(BLKIO_POLICY_PROP,
> BLKIO_PROP_weight),
> diff --git a/block/blk-cgroup.h b/block/blk-cgroup.h
> index ea4861b..0e9cd32 100644
> --- a/block/blk-cgroup.h
> +++ b/block/blk-cgroup.h
> @@ -73,10 +73,18 @@ enum blkg_state_flags {
> BLKG_empty,
> };
>
> +enum blkcg_class {
> + BLKIO_RT_CLASS = 1,
> + BLKIO_BE_CLASS = 2,
> +};
> +
> +#define BLKIO_DEFAULT_CLASS BLKIO_BE_CLASS
> +
> /* cgroup files owned by proportional weight policy */
> enum blkcg_file_name_prop {
> BLKIO_PROP_weight = 1,
> BLKIO_PROP_weight_device,
> + BLKIO_PROP_class,
> BLKIO_PROP_io_service_bytes,
> BLKIO_PROP_io_serviced,
> BLKIO_PROP_time,
> @@ -157,6 +165,21 @@ struct blkio_group {
> struct blkio_group_stats stats;
> };
>
> +struct proportion_policy {
> + unsigned int weight;
> + unsigned int class;
> +};
> +
> +union throttle_policy {
> + /*
> + * Rate read/write in terms of byptes per second
> + * Whether this rate represents read or write is determined
> + * by file type "fileid".
> + */
> + u64 bps;
> + unsigned int iops;
> +};
> +
> struct blkio_policy_node {
> struct list_head node;
> dev_t dev;
> @@ -166,14 +189,8 @@ struct blkio_policy_node {
> int fileid;
>
> union {
> - unsigned int weight;
> - /*
> - * Rate read/write in terms of byptes per second
> - * Whether this rate represents read or write is determined
> - * by file type "fileid".
> - */
> - u64 bps;
> - unsigned int iops;
> + struct proportion_policy prop;
> + union throttle_policy throtl;
> } val;
> };
>
> @@ -192,6 +209,8 @@ typedef void (blkio_unlink_group_fn) (void *key, struct blkio_group *blkg);
>
> typedef void (blkio_update_group_weight_fn) (void *key,
> struct blkio_group *blkg, unsigned int weight);
> +typedef void (blkio_update_group_class_fn) (void *key,
> + struct blkio_group *blkg, unsigned int class);
> typedef void (blkio_update_group_read_bps_fn) (void * key,
> struct blkio_group *blkg, u64 read_bps);
> typedef void (blkio_update_group_write_bps_fn) (void *key,
> @@ -204,6 +223,7 @@ typedef void (blkio_update_group_write_iops_fn) (void *key,
> struct blkio_policy_ops {
> blkio_unlink_group_fn *blkio_unlink_group_fn;
> blkio_update_group_weight_fn *blkio_update_group_weight_fn;
> + blkio_update_group_class_fn *blkio_update_group_class_fn;
> blkio_update_group_read_bps_fn *blkio_update_group_read_bps_fn;
> blkio_update_group_write_bps_fn *blkio_update_group_write_bps_fn;
> blkio_update_group_read_iops_fn *blkio_update_group_read_iops_fn;
> diff --git a/block/cfq-iosched.c b/block/cfq-iosched.c
> index ea83a4f..55e78b7 100644
> --- a/block/cfq-iosched.c
> +++ b/block/cfq-iosched.c
> @@ -179,6 +179,7 @@ struct cfq_group {
> /* group service_tree key */
> u64 vdisktime;
> unsigned int weight;
> + enum blkcg_class class;
>
> /* number of cfqq currently on this group */
> int nr_cfqq;
> @@ -988,6 +989,12 @@ void cfq_update_blkio_group_weight(void *key, struct blkio_group *blkg,
> cfqg_of_blkg(blkg)->weight = weight;
> }
>
> +void cfq_update_blkio_group_class(void *key, struct blkio_group *blkg,
> + unsigned int class)
> +{
> + cfqg_of_blkg(blkg)->class = class;
> +}
> +
> static struct cfq_group *
> cfq_find_alloc_cfqg(struct cfq_data *cfqd, struct cgroup *cgroup, int create)
> {
> @@ -4115,8 +4122,9 @@ static struct elevator_type iosched_cfq = {
> #ifdef CONFIG_CFQ_GROUP_IOSCHED
> static struct blkio_policy_type blkio_policy_cfq = {
> .ops = {
> - .blkio_unlink_group_fn = cfq_unlink_blkio_group,
> - .blkio_update_group_weight_fn = cfq_update_blkio_group_weight,
> + .blkio_unlink_group_fn = cfq_unlink_blkio_group,
> + .blkio_update_group_weight_fn = cfq_update_blkio_group_weight,
> + .blkio_update_group_class_fn = cfq_update_blkio_group_class,
> },
> .plid = BLKIO_POLICY_PROP,
> };
--
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