Re: [PATCH 1/2] workqueue: don't always set __WQ_ORDERED implicitly
On 6/29/20 8:37 AM, Lai Jiangshan wrote:
> On Mon, Jun 29, 2020 at 8:13 AM Bob Liu wrote:
>>
>> On 6/28/20 11:54 PM, Lai Jiangshan wrote:
>>> On Thu, Jun 11, 2020 at 6:29 PM Bob Liu wrote:
Current code always set 'Unbound && max_active == 1' workqueues to ordered
implicitly, while this may be not an expected behaviour for some use cases.
E.g some scsi and iscsi workqueues(unbound && max_active = 1) want to be
bind
to different cpu so as to get better isolation, but their cpumask can't be
changed because WQ_ORDERED is set implicitly.
>>>
>>> Hello
>>>
>>> If I read the code correctly, the reason why their cpumask can't
>>> be changed is because __WQ_ORDERED_EXPLICIT, not __WQ_ORDERED.
>>>
This patch adds a flag __WQ_ORDERED_DISABLE and also
create_singlethread_workqueue_noorder() to offer an new option.
Signed-off-by: Bob Liu
---
include/linux/workqueue.h | 4
kernel/workqueue.c| 4 +++-
2 files changed, 7 insertions(+), 1 deletion(-)
diff --git a/include/linux/workqueue.h b/include/linux/workqueue.h
index e48554e..4c86913 100644
--- a/include/linux/workqueue.h
+++ b/include/linux/workqueue.h
@@ -344,6 +344,7 @@ enum {
__WQ_ORDERED= 1 << 17, /* internal: workqueue is
ordered */
__WQ_LEGACY = 1 << 18, /* internal:
create*_workqueue() */
__WQ_ORDERED_EXPLICIT = 1 << 19, /* internal:
alloc_ordered_workqueue() */
+ __WQ_ORDERED_DISABLE= 1 << 20, /* internal: don't set
__WQ_ORDERED implicitly */
WQ_MAX_ACTIVE = 512,/* I like 512, better ideas? */
WQ_MAX_UNBOUND_PER_CPU = 4, /* 4 * #cpus for unbound wq */
@@ -433,6 +434,9 @@ struct workqueue_struct *alloc_workqueue(const char
*fmt,
#define create_singlethread_workqueue(name)\
alloc_ordered_workqueue("%s", __WQ_LEGACY | WQ_MEM_RECLAIM, name)
+#define create_singlethread_workqueue_noorder(name)\
+ alloc_workqueue("%s", WQ_SYSFS | __WQ_LEGACY | WQ_MEM_RECLAIM | \
+ WQ_UNBOUND | __WQ_ORDERED_DISABLE, 1, (name))
>>>
>>> I think using __WQ_ORDERED without __WQ_ORDERED_EXPLICIT is what you
>>> need, in which case cpumask is allowed to be changed.
>>>
>>
>> I don't think so, see function workqueue_apply_unbound_cpumask():
>>
>> wq_unbound_cpumask_store()
>> > workqueue_set_unbound_cpumask()
>>> workqueue_apply_unbound_cpumask() {
>> ...
>> 5276 /* creating multiple pwqs breaks ordering guarantee */
>> 5277 if (wq->flags & __WQ_ORDERED)
>> 5278 continue;
>>
>> Here will skip apply cpumask if only __WQ_ORDERED
>> is set.
>
> wq_unbound_cpumask_store() is for changing the cpumask of
> *all* workqueues. I don't think it can be used to make
> scsi and iscsi workqueues bound to different cpu.
>
> apply_workqueue_attrs() is for changing the cpumask of the specific
> workqueue, which can change the cpumask of __WQ_ORDERED workqueue
> (but without __WQ_ORDERED_EXPLICIT).
>
Yes, you are right. I made a mistake.
Sorry for the noise.
Regards,
Bob
>>
>> 5280 ctx = apply_wqattrs_prepare(wq, wq->unbound_attrs);
>>
>> }
Re: [PATCH 1/2] workqueue: don't always set __WQ_ORDERED implicitly
On 6/29/20 8:37 AM, Lai Jiangshan wrote:
> On Mon, Jun 29, 2020 at 8:13 AM Bob Liu wrote:
>>
>> On 6/28/20 11:54 PM, Lai Jiangshan wrote:
>>> On Thu, Jun 11, 2020 at 6:29 PM Bob Liu wrote:
Current code always set 'Unbound && max_active == 1' workqueues to ordered
implicitly, while this may be not an expected behaviour for some use cases.
E.g some scsi and iscsi workqueues(unbound && max_active = 1) want to be
bind
to different cpu so as to get better isolation, but their cpumask can't be
changed because WQ_ORDERED is set implicitly.
>>>
>>> Hello
>>>
>>> If I read the code correctly, the reason why their cpumask can't
>>> be changed is because __WQ_ORDERED_EXPLICIT, not __WQ_ORDERED.
>>>
This patch adds a flag __WQ_ORDERED_DISABLE and also
create_singlethread_workqueue_noorder() to offer an new option.
Signed-off-by: Bob Liu
---
include/linux/workqueue.h | 4
kernel/workqueue.c| 4 +++-
2 files changed, 7 insertions(+), 1 deletion(-)
diff --git a/include/linux/workqueue.h b/include/linux/workqueue.h
index e48554e..4c86913 100644
--- a/include/linux/workqueue.h
+++ b/include/linux/workqueue.h
@@ -344,6 +344,7 @@ enum {
__WQ_ORDERED= 1 << 17, /* internal: workqueue is
ordered */
__WQ_LEGACY = 1 << 18, /* internal:
create*_workqueue() */
__WQ_ORDERED_EXPLICIT = 1 << 19, /* internal:
alloc_ordered_workqueue() */
+ __WQ_ORDERED_DISABLE= 1 << 20, /* internal: don't set
__WQ_ORDERED implicitly */
WQ_MAX_ACTIVE = 512,/* I like 512, better ideas? */
WQ_MAX_UNBOUND_PER_CPU = 4, /* 4 * #cpus for unbound wq */
@@ -433,6 +434,9 @@ struct workqueue_struct *alloc_workqueue(const char
*fmt,
#define create_singlethread_workqueue(name)\
alloc_ordered_workqueue("%s", __WQ_LEGACY | WQ_MEM_RECLAIM, name)
+#define create_singlethread_workqueue_noorder(name)\
+ alloc_workqueue("%s", WQ_SYSFS | __WQ_LEGACY | WQ_MEM_RECLAIM | \
+ WQ_UNBOUND | __WQ_ORDERED_DISABLE, 1, (name))
>>>
>>> I think using __WQ_ORDERED without __WQ_ORDERED_EXPLICIT is what you
>>> need, in which case cpumask is allowed to be changed.
>>>
>>
>> I don't think so, see function workqueue_apply_unbound_cpumask():
>>
>> wq_unbound_cpumask_store()
>> > workqueue_set_unbound_cpumask()
>>> workqueue_apply_unbound_cpumask() {
>> ...
>> 5276 /* creating multiple pwqs breaks ordering guarantee */
>> 5277 if (wq->flags & __WQ_ORDERED)
>> 5278 continue;
>>
>> Here will skip apply cpumask if only __WQ_ORDERED
>> is set.
>
> wq_unbound_cpumask_store() is for changing the cpumask of
> *all* workqueues.
Isn't '/sys/bus/workqueue/devices//cpumask' using the same function to
change cpumask of
specific workqueue?
Am I missing something..
> I don't think it can be used to make
> scsi and iscsi workqueues bound to different cpu.
>
The idea is to register scsi/iscsi workqueues with WQ_SYSFS, and then they can
be bounded to different
cpu by writing cpu number to "/sys/bus/workqueue/devices//cpumask".
> apply_workqueue_attrs() is for changing the cpumask of the specific
> workqueue, which can change the cpumask of __WQ_ORDERED workqueue
> (but without __WQ_ORDERED_EXPLICIT).
>
>>
>> 5280 ctx = apply_wqattrs_prepare(wq, wq->unbound_attrs);
>>
>> }
>>
>> Thanks for your review.
>> Bob
>>
>>> Just use alloc_workqueue() with __WQ_ORDERED and max_active=1. It can
>>> be wrapped as a new function or macro, but I don't think>
>>> create_singlethread_workqueue_noorder() is a good name for it.
>>>
extern void destroy_workqueue(struct workqueue_struct *wq);
struct workqueue_attrs *alloc_workqueue_attrs(void);
diff --git a/kernel/workqueue.c b/kernel/workqueue.c
index 4e01c44..2167013 100644
--- a/kernel/workqueue.c
+++ b/kernel/workqueue.c
@@ -4237,7 +4237,9 @@ struct workqueue_struct *alloc_workqueue(const char
*fmt,
* on NUMA.
*/
if ((flags & WQ_UNBOUND) && max_active == 1)
- flags |= __WQ_ORDERED;
+ /* the caller may don't want __WQ_ORDERED to be set
implicitly. */
+ if (!(flags & __WQ_ORDERED_DISABLE))
+ flags |= __WQ_ORDERED;
/* see the comment above the definition of WQ_POWER_EFFICIENT */
if ((flags & WQ_POWER_EFFICIENT) && wq_power_efficient)
--
2.9.5
>>
Re: [PATCH 1/2] workqueue: don't always set __WQ_ORDERED implicitly
On Mon, Jun 29, 2020 at 8:13 AM Bob Liu wrote:
>
> On 6/28/20 11:54 PM, Lai Jiangshan wrote:
> > On Thu, Jun 11, 2020 at 6:29 PM Bob Liu wrote:
> >>
> >> Current code always set 'Unbound && max_active == 1' workqueues to ordered
> >> implicitly, while this may be not an expected behaviour for some use cases.
> >>
> >> E.g some scsi and iscsi workqueues(unbound && max_active = 1) want to be
> >> bind
> >> to different cpu so as to get better isolation, but their cpumask can't be
> >> changed because WQ_ORDERED is set implicitly.
> >
> > Hello
> >
> > If I read the code correctly, the reason why their cpumask can't
> > be changed is because __WQ_ORDERED_EXPLICIT, not __WQ_ORDERED.
> >
> >>
> >> This patch adds a flag __WQ_ORDERED_DISABLE and also
> >> create_singlethread_workqueue_noorder() to offer an new option.
> >>
> >> Signed-off-by: Bob Liu
> >> ---
> >> include/linux/workqueue.h | 4
> >> kernel/workqueue.c| 4 +++-
> >> 2 files changed, 7 insertions(+), 1 deletion(-)
> >>
> >> diff --git a/include/linux/workqueue.h b/include/linux/workqueue.h
> >> index e48554e..4c86913 100644
> >> --- a/include/linux/workqueue.h
> >> +++ b/include/linux/workqueue.h
> >> @@ -344,6 +344,7 @@ enum {
> >> __WQ_ORDERED= 1 << 17, /* internal: workqueue is
> >> ordered */
> >> __WQ_LEGACY = 1 << 18, /* internal:
> >> create*_workqueue() */
> >> __WQ_ORDERED_EXPLICIT = 1 << 19, /* internal:
> >> alloc_ordered_workqueue() */
> >> + __WQ_ORDERED_DISABLE= 1 << 20, /* internal: don't set
> >> __WQ_ORDERED implicitly */
> >>
> >> WQ_MAX_ACTIVE = 512,/* I like 512, better ideas? */
> >> WQ_MAX_UNBOUND_PER_CPU = 4, /* 4 * #cpus for unbound wq */
> >> @@ -433,6 +434,9 @@ struct workqueue_struct *alloc_workqueue(const char
> >> *fmt,
> >> #define create_singlethread_workqueue(name)\
> >> alloc_ordered_workqueue("%s", __WQ_LEGACY | WQ_MEM_RECLAIM, name)
> >>
> >> +#define create_singlethread_workqueue_noorder(name)\
> >> + alloc_workqueue("%s", WQ_SYSFS | __WQ_LEGACY | WQ_MEM_RECLAIM | \
> >> + WQ_UNBOUND | __WQ_ORDERED_DISABLE, 1, (name))
> >
> > I think using __WQ_ORDERED without __WQ_ORDERED_EXPLICIT is what you
> > need, in which case cpumask is allowed to be changed.
> >
>
> I don't think so, see function workqueue_apply_unbound_cpumask():
>
> wq_unbound_cpumask_store()
> > workqueue_set_unbound_cpumask()
>> workqueue_apply_unbound_cpumask() {
> ...
> 5276 /* creating multiple pwqs breaks ordering guarantee */
> 5277 if (wq->flags & __WQ_ORDERED)
> 5278 continue;
>
> Here will skip apply cpumask if only __WQ_ORDERED
> is set.
wq_unbound_cpumask_store() is for changing the cpumask of
*all* workqueues. I don't think it can be used to make
scsi and iscsi workqueues bound to different cpu.
apply_workqueue_attrs() is for changing the cpumask of the specific
workqueue, which can change the cpumask of __WQ_ORDERED workqueue
(but without __WQ_ORDERED_EXPLICIT).
>
> 5280 ctx = apply_wqattrs_prepare(wq, wq->unbound_attrs);
>
> }
>
> Thanks for your review.
> Bob
>
> > Just use alloc_workqueue() with __WQ_ORDERED and max_active=1. It can
> > be wrapped as a new function or macro, but I don't think>
> > create_singlethread_workqueue_noorder() is a good name for it.
> >
> >> extern void destroy_workqueue(struct workqueue_struct *wq);
> >>
> >> struct workqueue_attrs *alloc_workqueue_attrs(void);
> >> diff --git a/kernel/workqueue.c b/kernel/workqueue.c
> >> index 4e01c44..2167013 100644
> >> --- a/kernel/workqueue.c
> >> +++ b/kernel/workqueue.c
> >> @@ -4237,7 +4237,9 @@ struct workqueue_struct *alloc_workqueue(const char
> >> *fmt,
> >> * on NUMA.
> >> */
> >> if ((flags & WQ_UNBOUND) && max_active == 1)
> >> - flags |= __WQ_ORDERED;
> >> + /* the caller may don't want __WQ_ORDERED to be set
> >> implicitly. */
> >> + if (!(flags & __WQ_ORDERED_DISABLE))
> >> + flags |= __WQ_ORDERED;
> >>
> >> /* see the comment above the definition of WQ_POWER_EFFICIENT */
> >> if ((flags & WQ_POWER_EFFICIENT) && wq_power_efficient)
> >> --
> >> 2.9.5
> >>
>
Re: [PATCH 1/2] workqueue: don't always set __WQ_ORDERED implicitly
On 6/28/20 11:54 PM, Lai Jiangshan wrote:
> On Thu, Jun 11, 2020 at 6:29 PM Bob Liu wrote:
>>
>> Current code always set 'Unbound && max_active == 1' workqueues to ordered
>> implicitly, while this may be not an expected behaviour for some use cases.
>>
>> E.g some scsi and iscsi workqueues(unbound && max_active = 1) want to be bind
>> to different cpu so as to get better isolation, but their cpumask can't be
>> changed because WQ_ORDERED is set implicitly.
>
> Hello
>
> If I read the code correctly, the reason why their cpumask can't
> be changed is because __WQ_ORDERED_EXPLICIT, not __WQ_ORDERED.
>
>>
>> This patch adds a flag __WQ_ORDERED_DISABLE and also
>> create_singlethread_workqueue_noorder() to offer an new option.
>>
>> Signed-off-by: Bob Liu
>> ---
>> include/linux/workqueue.h | 4
>> kernel/workqueue.c| 4 +++-
>> 2 files changed, 7 insertions(+), 1 deletion(-)
>>
>> diff --git a/include/linux/workqueue.h b/include/linux/workqueue.h
>> index e48554e..4c86913 100644
>> --- a/include/linux/workqueue.h
>> +++ b/include/linux/workqueue.h
>> @@ -344,6 +344,7 @@ enum {
>> __WQ_ORDERED= 1 << 17, /* internal: workqueue is ordered
>> */
>> __WQ_LEGACY = 1 << 18, /* internal: create*_workqueue()
>> */
>> __WQ_ORDERED_EXPLICIT = 1 << 19, /* internal:
>> alloc_ordered_workqueue() */
>> + __WQ_ORDERED_DISABLE= 1 << 20, /* internal: don't set
>> __WQ_ORDERED implicitly */
>>
>> WQ_MAX_ACTIVE = 512,/* I like 512, better ideas? */
>> WQ_MAX_UNBOUND_PER_CPU = 4, /* 4 * #cpus for unbound wq */
>> @@ -433,6 +434,9 @@ struct workqueue_struct *alloc_workqueue(const char *fmt,
>> #define create_singlethread_workqueue(name)\
>> alloc_ordered_workqueue("%s", __WQ_LEGACY | WQ_MEM_RECLAIM, name)
>>
>> +#define create_singlethread_workqueue_noorder(name)\
>> + alloc_workqueue("%s", WQ_SYSFS | __WQ_LEGACY | WQ_MEM_RECLAIM | \
>> + WQ_UNBOUND | __WQ_ORDERED_DISABLE, 1, (name))
>
> I think using __WQ_ORDERED without __WQ_ORDERED_EXPLICIT is what you
> need, in which case cpumask is allowed to be changed.
>
I don't think so, see function workqueue_apply_unbound_cpumask():
wq_unbound_cpumask_store()
> workqueue_set_unbound_cpumask()
> workqueue_apply_unbound_cpumask() {
...
5276 /* creating multiple pwqs breaks ordering guarantee */
5277 if (wq->flags & __WQ_ORDERED)
5278 continue;
Here will skip apply cpumask if only __WQ_ORDERED is
set.
5280 ctx = apply_wqattrs_prepare(wq, wq->unbound_attrs);
}
Thanks for your review.
Bob
> Just use alloc_workqueue() with __WQ_ORDERED and max_active=1. It can
> be wrapped as a new function or macro, but I don't think>
> create_singlethread_workqueue_noorder() is a good name for it.
>
>> extern void destroy_workqueue(struct workqueue_struct *wq);
>>
>> struct workqueue_attrs *alloc_workqueue_attrs(void);
>> diff --git a/kernel/workqueue.c b/kernel/workqueue.c
>> index 4e01c44..2167013 100644
>> --- a/kernel/workqueue.c
>> +++ b/kernel/workqueue.c
>> @@ -4237,7 +4237,9 @@ struct workqueue_struct *alloc_workqueue(const char
>> *fmt,
>> * on NUMA.
>> */
>> if ((flags & WQ_UNBOUND) && max_active == 1)
>> - flags |= __WQ_ORDERED;
>> + /* the caller may don't want __WQ_ORDERED to be set
>> implicitly. */
>> + if (!(flags & __WQ_ORDERED_DISABLE))
>> + flags |= __WQ_ORDERED;
>>
>> /* see the comment above the definition of WQ_POWER_EFFICIENT */
>> if ((flags & WQ_POWER_EFFICIENT) && wq_power_efficient)
>> --
>> 2.9.5
>>
Re: [PATCH 1/2] workqueue: don't always set __WQ_ORDERED implicitly
On Thu, Jun 11, 2020 at 6:29 PM Bob Liu wrote:
>
> Current code always set 'Unbound && max_active == 1' workqueues to ordered
> implicitly, while this may be not an expected behaviour for some use cases.
>
> E.g some scsi and iscsi workqueues(unbound && max_active = 1) want to be bind
> to different cpu so as to get better isolation, but their cpumask can't be
> changed because WQ_ORDERED is set implicitly.
Hello
If I read the code correctly, the reason why their cpumask can't
be changed is because __WQ_ORDERED_EXPLICIT, not __WQ_ORDERED.
>
> This patch adds a flag __WQ_ORDERED_DISABLE and also
> create_singlethread_workqueue_noorder() to offer an new option.
>
> Signed-off-by: Bob Liu
> ---
> include/linux/workqueue.h | 4
> kernel/workqueue.c| 4 +++-
> 2 files changed, 7 insertions(+), 1 deletion(-)
>
> diff --git a/include/linux/workqueue.h b/include/linux/workqueue.h
> index e48554e..4c86913 100644
> --- a/include/linux/workqueue.h
> +++ b/include/linux/workqueue.h
> @@ -344,6 +344,7 @@ enum {
> __WQ_ORDERED= 1 << 17, /* internal: workqueue is ordered
> */
> __WQ_LEGACY = 1 << 18, /* internal: create*_workqueue() */
> __WQ_ORDERED_EXPLICIT = 1 << 19, /* internal:
> alloc_ordered_workqueue() */
> + __WQ_ORDERED_DISABLE= 1 << 20, /* internal: don't set
> __WQ_ORDERED implicitly */
>
> WQ_MAX_ACTIVE = 512,/* I like 512, better ideas? */
> WQ_MAX_UNBOUND_PER_CPU = 4, /* 4 * #cpus for unbound wq */
> @@ -433,6 +434,9 @@ struct workqueue_struct *alloc_workqueue(const char *fmt,
> #define create_singlethread_workqueue(name)\
> alloc_ordered_workqueue("%s", __WQ_LEGACY | WQ_MEM_RECLAIM, name)
>
> +#define create_singlethread_workqueue_noorder(name)\
> + alloc_workqueue("%s", WQ_SYSFS | __WQ_LEGACY | WQ_MEM_RECLAIM | \
> + WQ_UNBOUND | __WQ_ORDERED_DISABLE, 1, (name))
I think using __WQ_ORDERED without __WQ_ORDERED_EXPLICIT is what you
need, in which case cpumask is allowed to be changed.
Just use alloc_workqueue() with __WQ_ORDERED and max_active=1. It can
be wrapped as a new function or macro, but I don't think
create_singlethread_workqueue_noorder() is a good name for it.
> extern void destroy_workqueue(struct workqueue_struct *wq);
>
> struct workqueue_attrs *alloc_workqueue_attrs(void);
> diff --git a/kernel/workqueue.c b/kernel/workqueue.c
> index 4e01c44..2167013 100644
> --- a/kernel/workqueue.c
> +++ b/kernel/workqueue.c
> @@ -4237,7 +4237,9 @@ struct workqueue_struct *alloc_workqueue(const char
> *fmt,
> * on NUMA.
> */
> if ((flags & WQ_UNBOUND) && max_active == 1)
> - flags |= __WQ_ORDERED;
> + /* the caller may don't want __WQ_ORDERED to be set
> implicitly. */
> + if (!(flags & __WQ_ORDERED_DISABLE))
> + flags |= __WQ_ORDERED;
>
> /* see the comment above the definition of WQ_POWER_EFFICIENT */
> if ((flags & WQ_POWER_EFFICIENT) && wq_power_efficient)
> --
> 2.9.5
>
Re: [PATCH 1/2] workqueue: don't always set __WQ_ORDERED implicitly
ping..
On 6/11/20 6:07 PM, Bob Liu wrote:
> Current code always set 'Unbound && max_active == 1' workqueues to ordered
> implicitly, while this may be not an expected behaviour for some use cases.
>
> E.g some scsi and iscsi workqueues(unbound && max_active = 1) want to be bind
> to different cpu so as to get better isolation, but their cpumask can't be
> changed because WQ_ORDERED is set implicitly.
>
> This patch adds a flag __WQ_ORDERED_DISABLE and also
> create_singlethread_workqueue_noorder() to offer an new option.
>
> Signed-off-by: Bob Liu
> ---
> include/linux/workqueue.h | 4
> kernel/workqueue.c| 4 +++-
> 2 files changed, 7 insertions(+), 1 deletion(-)
>
> diff --git a/include/linux/workqueue.h b/include/linux/workqueue.h
> index e48554e..4c86913 100644
> --- a/include/linux/workqueue.h
> +++ b/include/linux/workqueue.h
> @@ -344,6 +344,7 @@ enum {
> __WQ_ORDERED= 1 << 17, /* internal: workqueue is ordered */
> __WQ_LEGACY = 1 << 18, /* internal: create*_workqueue() */
> __WQ_ORDERED_EXPLICIT = 1 << 19, /* internal:
> alloc_ordered_workqueue() */
> + __WQ_ORDERED_DISABLE= 1 << 20, /* internal: don't set __WQ_ORDERED
> implicitly */
>
> WQ_MAX_ACTIVE = 512,/* I like 512, better ideas? */
> WQ_MAX_UNBOUND_PER_CPU = 4, /* 4 * #cpus for unbound wq */
> @@ -433,6 +434,9 @@ struct workqueue_struct *alloc_workqueue(const char *fmt,
> #define create_singlethread_workqueue(name) \
> alloc_ordered_workqueue("%s", __WQ_LEGACY | WQ_MEM_RECLAIM, name)
>
> +#define create_singlethread_workqueue_noorder(name) \
> + alloc_workqueue("%s", WQ_SYSFS | __WQ_LEGACY | WQ_MEM_RECLAIM | \
> + WQ_UNBOUND | __WQ_ORDERED_DISABLE, 1, (name))
> extern void destroy_workqueue(struct workqueue_struct *wq);
>
> struct workqueue_attrs *alloc_workqueue_attrs(void);
> diff --git a/kernel/workqueue.c b/kernel/workqueue.c
> index 4e01c44..2167013 100644
> --- a/kernel/workqueue.c
> +++ b/kernel/workqueue.c
> @@ -4237,7 +4237,9 @@ struct workqueue_struct *alloc_workqueue(const char
> *fmt,
>* on NUMA.
>*/
> if ((flags & WQ_UNBOUND) && max_active == 1)
> - flags |= __WQ_ORDERED;
> + /* the caller may don't want __WQ_ORDERED to be set implicitly.
> */
> + if (!(flags & __WQ_ORDERED_DISABLE))
> + flags |= __WQ_ORDERED;
>
> /* see the comment above the definition of WQ_POWER_EFFICIENT */
> if ((flags & WQ_POWER_EFFICIENT) && wq_power_efficient)
>
[PATCH 1/2] workqueue: don't always set __WQ_ORDERED implicitly
Current code always set 'Unbound && max_active == 1' workqueues to ordered
implicitly, while this may be not an expected behaviour for some use cases.
E.g some scsi and iscsi workqueues(unbound && max_active = 1) want to be bind
to different cpu so as to get better isolation, but their cpumask can't be
changed because WQ_ORDERED is set implicitly.
This patch adds a flag __WQ_ORDERED_DISABLE and also
create_singlethread_workqueue_noorder() to offer an new option.
Signed-off-by: Bob Liu
---
include/linux/workqueue.h | 4
kernel/workqueue.c| 4 +++-
2 files changed, 7 insertions(+), 1 deletion(-)
diff --git a/include/linux/workqueue.h b/include/linux/workqueue.h
index e48554e..4c86913 100644
--- a/include/linux/workqueue.h
+++ b/include/linux/workqueue.h
@@ -344,6 +344,7 @@ enum {
__WQ_ORDERED= 1 << 17, /* internal: workqueue is ordered */
__WQ_LEGACY = 1 << 18, /* internal: create*_workqueue() */
__WQ_ORDERED_EXPLICIT = 1 << 19, /* internal:
alloc_ordered_workqueue() */
+ __WQ_ORDERED_DISABLE= 1 << 20, /* internal: don't set __WQ_ORDERED
implicitly */
WQ_MAX_ACTIVE = 512,/* I like 512, better ideas? */
WQ_MAX_UNBOUND_PER_CPU = 4, /* 4 * #cpus for unbound wq */
@@ -433,6 +434,9 @@ struct workqueue_struct *alloc_workqueue(const char *fmt,
#define create_singlethread_workqueue(name)\
alloc_ordered_workqueue("%s", __WQ_LEGACY | WQ_MEM_RECLAIM, name)
+#define create_singlethread_workqueue_noorder(name)\
+ alloc_workqueue("%s", WQ_SYSFS | __WQ_LEGACY | WQ_MEM_RECLAIM | \
+ WQ_UNBOUND | __WQ_ORDERED_DISABLE, 1, (name))
extern void destroy_workqueue(struct workqueue_struct *wq);
struct workqueue_attrs *alloc_workqueue_attrs(void);
diff --git a/kernel/workqueue.c b/kernel/workqueue.c
index 4e01c44..2167013 100644
--- a/kernel/workqueue.c
+++ b/kernel/workqueue.c
@@ -4237,7 +4237,9 @@ struct workqueue_struct *alloc_workqueue(const char *fmt,
* on NUMA.
*/
if ((flags & WQ_UNBOUND) && max_active == 1)
- flags |= __WQ_ORDERED;
+ /* the caller may don't want __WQ_ORDERED to be set implicitly.
*/
+ if (!(flags & __WQ_ORDERED_DISABLE))
+ flags |= __WQ_ORDERED;
/* see the comment above the definition of WQ_POWER_EFFICIENT */
if ((flags & WQ_POWER_EFFICIENT) && wq_power_efficient)
--
2.9.5
