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SubjectRe: [PATCH] IO Controller: Add per-device weight and ioprio_class handling
Vivek Goyal wrote:
> On Wed, May 13, 2009 at 10:00:21AM +0800, Gui Jianfeng wrote:
>> Hi Vivek,
>>
>> This patch enables per-cgroup per-device weight and ioprio_class handling.
>> A new cgroup interface "policy" is introduced. You can make use of this
>> file to configure weight and ioprio_class for each device in a given cgroup.
>> The original "weight" and "ioprio_class" files are still available. If you
>> don't do special configuration for a particular device, "weight" and
>> "ioprio_class" are used as default values in this device.
>>
>> You can use the following format to play with the new interface.
>> #echo DEV:weight:ioprio_class > /patch/to/cgroup/policy
>> weight=0 means removing the policy for DEV.
>>
>> Examples:
>> Configure weight=300 ioprio_class=2 on /dev/hdb in this cgroup
>> # echo /dev/hdb:300:2 > io.policy
>> # cat io.policy
>> dev weight class
>> /dev/hdb 300 2
>>
>> Configure weight=500 ioprio_class=1 on /dev/hda in this cgroup
>> # echo /dev/hda:500:1 > io.policy
>> # cat io.policy
>> dev weight class
>> /dev/hda 500 1
>> /dev/hdb 300 2
>>
>> Remove the policy for /dev/hda in this cgroup
>> # echo /dev/hda:0:1 > io.policy
>> # cat io.policy
>> dev weight class
>> /dev/hdb 300 2
>>
>
> Hi Gui,
>
> Noticed few things during testing.
>
> 1. Writing 0 as weight is not removing the policy for me, if I swich the
> IO scheduler on the device.
>
> - echo "/dev/sdb:500:2" > io.policy
> - Change elevator on device /sdb
> - echo "/dev/sdb:0:2" > io.policy
> - cat io.policy
> The old rule is not gone away.
>
> 2. One can add same rule twice after chaning elevator.
>
> - echo "/dev/sdb:500:2" > io.policy
> - Change elevator on device /sdb
> - echo "/dev/sdb:500:2" > io.policy
> - cat io.policy
>
> Same rule appears twice
>
> 3. If one writes to io.weight, it should not update the weight for a
> device if there is a rule for the device already. For example, if a
> cgroup got io.weight=1000 and later i set the weight on /dev/sdb to
> 500 and then change the io.weight=200, it should not be udpated for
> for groups on /dev/sdb. Why?, because I think it will make more sense
> to keep the simple rule that as long there is a rule for device, it
> always overrides the generic settings of io.weight.
>
> 4. Wrong rule should return invalid value instead we see oops.
>
> - echo "/dev/sdb:0:" > io.policy

Hi Vivek,

Thanks for testing, i'll fix the above problems, and send an update version.

>
> [ 2651.587533] BUG: unable to handle kernel NULL pointer dereference at
> (null)
> [ 2651.588301] IP: [<ffffffff811f035c>] strict_strtoul+0x24/0x79
> [ 2651.588301] PGD 38c33067 PUD 38d67067 PMD 0
> [ 2651.588301] Oops: 0000 [#2] SMP
> [ 2651.588301] last sysfs file:
> /sys/devices/pci0000:00/0000:00:1c.0/0000:0e:00.0/irq
> [ 2651.588301] CPU 2
> [ 2651.588301] Modules linked in:
> [ 2651.588301] Pid: 4538, comm: bash Tainted: G D 2.6.30-rc4-ioc
> #52 HP xw6600 Workstation
> [ 2651.588301] RIP: 0010:[<ffffffff811f035c>] [<ffffffff811f035c>]
> strict_strtoul+0x24/0x79
> [ 2651.588301] RSP: 0018:ffff88003dd73dc0 EFLAGS: 00010286
> [ 2651.588301] RAX: 0000000000000000 RBX: 0000000000000000 RCX:
> ffffffffffffffff
> [ 2651.588301] RDX: ffff88003e9ffca0 RSI: 000000000000000a RDI:
> 0000000000000000
> [ 2651.588301] RBP: ffff88003dd73de8 R08: 000000000000000a R09:
> ffff88003dd73cf8
> [ 2651.588301] R10: ffff88003dcd2300 R11: ffffffff8178aa00 R12:
> ffff88003f4a1e00
> [ 2651.588301] R13: ffff88003e9ffca0 R14: ffff88003ac5f200 R15:
> ffff88003fa7ed40
> [ 2651.588301] FS: 00007ff971c466f0(0000) GS:ffff88000209c000(0000)
> knlGS:0000000000000000
> [ 2651.588301] CS: 0010 DS: 0000 ES: 0000 CR0: 000000008005003b
> [ 2651.588301] CR2: 0000000000000000 CR3: 000000003ad0d000 CR4:
> 00000000000006e0
> [ 2651.588301] DR0: 0000000000000000 DR1: 0000000000000000 DR2:
> 0000000000000000
> [ 2651.588301] DR3: 0000000000000000 DR6: 00000000ffff0ff0 DR7:
> 0000000000000400
> [ 2651.588301] Process bash (pid: 4538, threadinfo ffff88003dd72000, task
> ffff880038d98000)
> [ 2651.588301] Stack:
> [ 2651.588301] ffffffff810d8f23 ffff88003fa7ed4a ffff88003dcdeee0
> ffff88003f4a1e00
> [ 2651.588301] ffff88003e9ffc60 ffff88003dd73e68 ffffffff811e8097
> ffff880038dd2780
> [ 2651.588301] ffff88003dd73e48 ffff88003fa7ed40 ffff88003fa7ed49
> 0000000000000000
> [ 2651.588301] Call Trace:
> [ 2651.588301] [<ffffffff810d8f23>] ? iput+0x2f/0x65
> [ 2651.588301] [<ffffffff811e8097>] io_cgroup_policy_write+0x11d/0x2ac
> [ 2651.588301] [<ffffffff81072dee>] cgroup_file_write+0x1ec/0x254
> [ 2651.588301] [<ffffffff811afce8>] ? security_file_permission+0x11/0x13
> [ 2651.588301] [<ffffffff810c8394>] vfs_write+0xab/0x105
> [ 2651.588301] [<ffffffff810c84a8>] sys_write+0x47/0x6c
> [ 2651.588301] [<ffffffff8100bb2b>] system_call_fastpath+0x16/0x1b
> [ 2651.588301] Code: 65 ff ff ff 5b c9 c3 55 48 83 c9 ff 31 c0 fc 48 89 e5
> 41 55 41 89 f0 49 89 d5 41 54 53 48 89 fb 48 83 ec 10 48 c7 02 00 00 00 00
> <f2> ae 48 f7 d1 49 89 cc 49 ff cc 74 39 48 8d 75 e0 44 89 c2 48
> [ 2651.588301] RIP [<ffffffff811f035c>] strict_strtoul+0x24/0x79
> [ 2651.588301] RSP <ffff88003dd73dc0>
> [ 2651.588301] CR2: 0000000000000000
> [ 2651.828110] ---[ end trace 537b9a98ce297f01 ]---
>
> Thanks
> Vivek
>
>> Signed-off-by: Gui Jianfeng <guijianfeng@cn.fujitsu.com>
>> ---
>> block/elevator-fq.c | 239 +++++++++++++++++++++++++++++++++++++++++++++++++-
>> block/elevator-fq.h | 11 +++
>> 2 files changed, 245 insertions(+), 5 deletions(-)
>>
>> diff --git a/block/elevator-fq.c b/block/elevator-fq.c
>> index 69435ab..7c95d55 100644
>> --- a/block/elevator-fq.c
>> +++ b/block/elevator-fq.c
>> @@ -12,6 +12,9 @@
>> #include "elevator-fq.h"
>> #include <linux/blktrace_api.h>
>> #include <linux/biotrack.h>
>> +#include <linux/seq_file.h>
>> +#include <linux/genhd.h>
>> +
>>
>> /* Values taken from cfq */
>> const int elv_slice_sync = HZ / 10;
>> @@ -1045,12 +1048,30 @@ struct io_group *io_lookup_io_group_current(struct request_queue *q)
>> }
>> EXPORT_SYMBOL(io_lookup_io_group_current);
>>
>> -void io_group_init_entity(struct io_cgroup *iocg, struct io_group *iog)
>> +static struct policy_node *policy_search_node(const struct io_cgroup *iocg,
>> + void *key);
>> +
>> +void io_group_init_entity(struct io_cgroup *iocg, struct io_group *iog,
>> + void *key)
>> {
>> struct io_entity *entity = &iog->entity;
>> + struct policy_node *pn;
>> +
>> + spin_lock_irq(&iocg->lock);
>> + pn = policy_search_node(iocg, key);
>> + if (pn) {
>> + entity->weight = pn->weight;
>> + entity->new_weight = pn->weight;
>> + entity->ioprio_class = pn->ioprio_class;
>> + entity->new_ioprio_class = pn->ioprio_class;
>> + } else {
>> + entity->weight = iocg->weight;
>> + entity->new_weight = iocg->weight;
>> + entity->ioprio_class = iocg->ioprio_class;
>> + entity->new_ioprio_class = iocg->ioprio_class;
>> + }
>> + spin_unlock_irq(&iocg->lock);
>>
>> - entity->weight = entity->new_weight = iocg->weight;
>> - entity->ioprio_class = entity->new_ioprio_class = iocg->ioprio_class;
>> entity->ioprio_changed = 1;
>> entity->my_sched_data = &iog->sched_data;
>> }
>> @@ -1263,7 +1284,7 @@ struct io_group *io_group_chain_alloc(struct request_queue *q, void *key,
>> atomic_set(&iog->ref, 0);
>> iog->deleting = 0;
>>
>> - io_group_init_entity(iocg, iog);
>> + io_group_init_entity(iocg, iog, key);
>> iog->my_entity = &iog->entity;
>> #ifdef CONFIG_DEBUG_GROUP_IOSCHED
>> iog->iocg_id = css_id(&iocg->css);
>> @@ -1549,8 +1570,208 @@ struct io_group *io_alloc_root_group(struct request_queue *q,
>> return iog;
>> }
>>
>> +static int io_cgroup_policy_read(struct cgroup *cgrp, struct cftype *cft,
>> + struct seq_file *m)
>> +{
>> + struct io_cgroup *iocg;
>> + struct policy_node *pn;
>> +
>> + iocg = cgroup_to_io_cgroup(cgrp);
>> +
>> + if (list_empty(&iocg->list))
>> + goto out;
>> +
>> + seq_printf(m, "dev weight class\n");
>> +
>> + spin_lock_irq(&iocg->lock);
>> + list_for_each_entry(pn, &iocg->list, node) {
>> + seq_printf(m, "%s %lu %lu\n", pn->dev_name,
>> + pn->weight, pn->ioprio_class);
>> + }
>> + spin_unlock_irq(&iocg->lock);
>> +out:
>> + return 0;
>> +}
>> +
>> +static inline void policy_insert_node(struct io_cgroup *iocg,
>> + struct policy_node *pn)
>> +{
>> + list_add(&pn->node, &iocg->list);
>> +}
>> +
>> +/* Must be called with iocg->lock held */
>> +static inline void policy_delete_node(struct policy_node *pn)
>> +{
>> + list_del(&pn->node);
>> +}
>> +
>> +/* Must be called with iocg->lock held */
>> +static struct policy_node *policy_search_node(const struct io_cgroup *iocg,
>> + void *key)
>> +{
>> + struct policy_node *pn;
>> +
>> + if (list_empty(&iocg->list))
>> + return NULL;
>> +
>> + list_for_each_entry(pn, &iocg->list, node) {
>> + if (pn->key == key)
>> + return pn;
>> + }
>> +
>> + return NULL;
>> +}
>> +
>> +static void *devname_to_efqd(const char *buf)
>> +{
>> + struct block_device *bdev;
>> + void *key = NULL;
>> + struct gendisk *disk;
>> + int part;
>> +
>> + bdev = lookup_bdev(buf);
>> + if (IS_ERR(bdev))
>> + return NULL;
>> +
>> + disk = get_gendisk(bdev->bd_dev, &part);
>> + key = (void *)&disk->queue->elevator->efqd;
>> + bdput(bdev);
>> +
>> + return key;
>> +}
>> +
>> +static int policy_parse_and_set(char *buf, struct policy_node *newpn)
>> +{
>> + char *s[3];
>> + char *p;
>> + int ret;
>> + int i = 0;
>> +
>> + memset(s, 0, sizeof(s));
>> + while (i < ARRAY_SIZE(s)) {
>> + p = strsep(&buf, ":");
>> + if (!p)
>> + break;
>> + if (!*p)
>> + continue;
>> + s[i++] = p;
>> + }
>> +
>> + newpn->key = devname_to_efqd(s[0]);
>> + if (!newpn->key)
>> + return -EINVAL;
>> +
>> + strcpy(newpn->dev_name, s[0]);
>> +
>> + ret = strict_strtoul(s[1], 10, &newpn->weight);
>> + if (ret || newpn->weight > WEIGHT_MAX)
>> + return -EINVAL;
>> +
>> + ret = strict_strtoul(s[2], 10, &newpn->ioprio_class);
>> + if (ret || newpn->ioprio_class < IOPRIO_CLASS_RT ||
>> + newpn->ioprio_class > IOPRIO_CLASS_IDLE)
>> + return -EINVAL;
>> +
>> + return 0;
>> +}
>> +
>> +static int io_cgroup_policy_write(struct cgroup *cgrp, struct cftype *cft,
>> + const char *buffer)
>> +{
>> + struct io_cgroup *iocg;
>> + struct policy_node *newpn, *pn;
>> + char *buf;
>> + int ret = 0;
>> + int keep_newpn = 0;
>> + struct hlist_node *n;
>> + struct io_group *iog;
>> +
>> + buf = kstrdup(buffer, GFP_KERNEL);
>> + if (!buf)
>> + return -ENOMEM;
>> +
>> + newpn = kzalloc(sizeof(*newpn), GFP_KERNEL);
>> + if (!newpn) {
>> + ret = -ENOMEM;
>> + goto free_buf;
>> + }
>> +
>> + ret = policy_parse_and_set(buf, newpn);
>> + if (ret)
>> + goto free_newpn;
>> +
>> + if (!cgroup_lock_live_group(cgrp)) {
>> + ret = -ENODEV;
>> + goto free_newpn;
>> + }
>> +
>> + iocg = cgroup_to_io_cgroup(cgrp);
>> + spin_lock_irq(&iocg->lock);
>> +
>> + pn = policy_search_node(iocg, newpn->key);
>> + if (!pn) {
>> + if (newpn->weight != 0) {
>> + policy_insert_node(iocg, newpn);
>> + keep_newpn = 1;
>> + }
>> + goto update_io_group;
>> + }
>> +
>> + if (newpn->weight == 0) {
>> + /* weight == 0 means deleteing a policy */
>> + policy_delete_node(pn);
>> + goto update_io_group;
>> + }
>> +
>> + pn->weight = newpn->weight;
>> + pn->ioprio_class = newpn->ioprio_class;
>> +
>> +update_io_group:
>> + hlist_for_each_entry(iog, n, &iocg->group_data, group_node) {
>> + if (iog->key == newpn->key) {
>> + if (newpn->weight) {
>> + iog->entity.new_weight = newpn->weight;
>> + iog->entity.new_ioprio_class =
>> + newpn->ioprio_class;
>> + /*
>> + * iog weight and ioprio_class updating
>> + * actually happens if ioprio_changed is set.
>> + * So ensure ioprio_changed is not set until
>> + * new weight and new ioprio_class are updated.
>> + */
>> + smp_wmb();
>> + iog->entity.ioprio_changed = 1;
>> + } else {
>> + iog->entity.new_weight = iocg->weight;
>> + iog->entity.new_ioprio_class =
>> + iocg->ioprio_class;
>> +
>> + /* The same as above */
>> + smp_wmb();
>> + iog->entity.ioprio_changed = 1;
>> + }
>> + }
>> + }
>> + spin_unlock_irq(&iocg->lock);
>> +
>> + cgroup_unlock();
>> +
>> +free_newpn:
>> + if (!keep_newpn)
>> + kfree(newpn);
>> +free_buf:
>> + kfree(buf);
>> + return ret;
>> +}
>> +
>> struct cftype bfqio_files[] = {
>> {
>> + .name = "policy",
>> + .read_seq_string = io_cgroup_policy_read,
>> + .write_string = io_cgroup_policy_write,
>> + .max_write_len = 256,
>> + },
>> + {
>> .name = "weight",
>> .read_u64 = io_cgroup_weight_read,
>> .write_u64 = io_cgroup_weight_write,
>> @@ -1592,6 +1813,7 @@ struct cgroup_subsys_state *iocg_create(struct cgroup_subsys *subsys,
>> INIT_HLIST_HEAD(&iocg->group_data);
>> iocg->weight = IO_DEFAULT_GRP_WEIGHT;
>> iocg->ioprio_class = IO_DEFAULT_GRP_CLASS;
>> + INIT_LIST_HEAD(&iocg->list);
>>
>> return &iocg->css;
>> }
>> @@ -1750,6 +1972,7 @@ void iocg_destroy(struct cgroup_subsys *subsys, struct cgroup *cgroup)
>> unsigned long flags, flags1;
>> int queue_lock_held = 0;
>> struct elv_fq_data *efqd;
>> + struct policy_node *pn, *pntmp;
>>
>> /*
>> * io groups are linked in two lists. One list is maintained
>> @@ -1823,6 +2046,12 @@ locked:
>> BUG_ON(!hlist_empty(&iocg->group_data));
>>
>> free_css_id(&io_subsys, &iocg->css);
>> +
>> + list_for_each_entry_safe(pn, pntmp, &iocg->list, node) {
>> + policy_delete_node(pn);
>> + kfree(pn);
>> + }
>> +
>> kfree(iocg);
>> }
>>
>> @@ -2137,7 +2366,7 @@ void elv_fq_unset_request_ioq(struct request_queue *q, struct request *rq)
>> void bfq_init_entity(struct io_entity *entity, struct io_group *iog)
>> {
>> entity->ioprio = entity->new_ioprio;
>> - entity->weight = entity->new_weight;
>> + entity->weight = entity->new_weigh;
>> entity->ioprio_class = entity->new_ioprio_class;
>> entity->sched_data = &iog->sched_data;
>> }
>> diff --git a/block/elevator-fq.h b/block/elevator-fq.h
>> index db3a347..0407633 100644
>> --- a/block/elevator-fq.h
>> +++ b/block/elevator-fq.h
>> @@ -253,6 +253,14 @@ struct io_group {
>> #endif
>> };
>>
>> +struct policy_node {
>> + struct list_head node;
>> + char dev_name[32];
>> + void *key;
>> + unsigned long weight;
>> + unsigned long ioprio_class;
>> +};
>> +
>> /**
>> * struct bfqio_cgroup - bfq cgroup data structure.
>> * @css: subsystem state for bfq in the containing cgroup.
>> @@ -269,6 +277,9 @@ struct io_cgroup {
>>
>> unsigned long weight, ioprio_class;
>>
>> + /* list of policy_node */
>> + struct list_head list;
>> +
>> spinlock_t lock;
>> struct hlist_head group_data;
>> };
>> --
>> 1.5.4.rc3
>>
>>
>
>
>

--
Regards
Gui Jianfeng



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