* [PATCH 0/5] cpusets: dynamical scheduler domain flags
@ 2012-07-17 9:03 Michael Wang
2012-07-20 16:42 ` Peter Zijlstra
0 siblings, 1 reply; 5+ messages in thread
From: Michael Wang @ 2012-07-17 9:03 UTC (permalink / raw)
To: LKML; +Cc: mingo, Peter Zijlstra, paul
From: Michael Wang <wangyun@linux.vnet.ibm.com>
This patch set provide a way for user to dynamically configure the scheduler
domain flags, which usually to be static.
We can do the configuration through cpuset cgroup, new file will be found
under each hierarchy:
sched_smt_domain_flag
-- appear when CONFIG_SCHED_SMT enabled, stands for the domain flags
of cpuset on smt level
sched_mc_domain_flag
-- appear when CONFIG_SCHED_MC enabled, stands for the domain flags
of cpuset on mc level
sched_book_domain_flag
-- appear when CONFIG_SCHED_BOOK enabled, stands for the domain flags
of cpuset on book level
sched_cpu_domain_flag
-- stands for the domain flags of cpuset on cpu level
sched_enable_domain_flag
-- set to 1 if want to use the dynamical domain flags, domain will
be rebuild
Examples:
Currently the domain flags bit are:
#define SD_LOAD_BALANCE 0x0001 /* Do load balancing on this domain. */
#define SD_BALANCE_NEWIDLE 0x0002 /* Balance when about to become idle */
#define SD_BALANCE_EXEC 0x0004 /* Balance on exec */
#define SD_BALANCE_FORK 0x0008 /* Balance on fork, clone */
#define SD_BALANCE_WAKE 0x0010 /* Balance on wakeup */
#define SD_WAKE_AFFINE 0x0020 /* Wake task to waking CPU */
#define SD_PREFER_LOCAL 0x0040 /* Prefer to keep tasks local to this domain */
#define SD_SHARE_CPUPOWER 0x0080 /* Domain members share cpu power */
#define SD_SHARE_PKG_RESOURCES 0x0200 /* Domain members share cpu pkg resources */
#define SD_SERIALIZE 0x0400 /* Only a single load balancing instance */
#define SD_ASYM_PACKING 0x0800 /* Place busy groups earlier in the domain */
#define SD_PREFER_SIBLING 0x1000 /* Prefer to place tasks in a sibling domain */
#define SD_OVERLAP 0x2000 /* sched_domains of this level overlap */
#define SD_NUMA 0x4000 /* cross-node balancing */
If we want to set SMT domain to be:
'SD_LOAD_BALANCE | SD_BALANCE_WAKE | SD_OVERLAP'
and other level domain only has SD_LOAD_BALANCE, then we can use:
echo 0x1011 > /sys/fs/cgroup/cpuset/cpuset.sched_smt_domain_flag
echo 0x1 > /sys/fs/cgroup/cpuset/cpuset.sched_mc_domain_flag
echo 0x1 > /sys/fs/cgroup/cpuset/cpuset.sched_book_domain_flag
echo 0x1 > /sys/fs/cgroup/cpuset/cpuset.sched_cpu_domain_flag
echo 1 > /sys/fs/cgroup/cpuset/cpuset.sched_enable_domain_flag
including:
cpusets: add basic variables
cpusets: add functions and code for initialization
cpusets: enable the dynamical domain flags
cpusets: add fundamental functions for recording
cpusets: add the configuration facility
Signed-off-by: Michael Wang <wangyun@linux.vnet.ibm.com>
---
b/include/linux/sched.h | 22 ++++++++
b/kernel/cpuset.c | 7 ++
b/kernel/sched/core.c | 2
include/linux/sched.h | 10 ++-
kernel/cpuset.c | 131 +++++++++++++++++++++++++++++++++++++++++++++++-
kernel/sched/core.c | 10 +++
6 files changed, 176 insertions(+), 6 deletions(-)
^ permalink raw reply [flat|nested] 5+ messages in thread
* Re: [PATCH 0/5] cpusets: dynamical scheduler domain flags
2012-07-17 9:03 [PATCH 0/5] cpusets: dynamical scheduler domain flags Michael Wang
@ 2012-07-20 16:42 ` Peter Zijlstra
2012-07-23 2:30 ` Michael Wang
0 siblings, 1 reply; 5+ messages in thread
From: Peter Zijlstra @ 2012-07-20 16:42 UTC (permalink / raw)
To: Michael Wang; +Cc: LKML, mingo, paul
On Tue, 2012-07-17 at 17:03 +0800, Michael Wang wrote:
> This patch set provide a way for user to dynamically configure the scheduler
> domain flags, which usually to be static.
NAK.. you don't get to expose all this nonsense in a 'stable' ABI.
You shouldn't need to prod at them to begin with.
^ permalink raw reply [flat|nested] 5+ messages in thread
* Re: [PATCH 0/5] cpusets: dynamical scheduler domain flags
2012-07-20 16:42 ` Peter Zijlstra
@ 2012-07-23 2:30 ` Michael Wang
2012-07-23 4:28 ` Mike Galbraith
0 siblings, 1 reply; 5+ messages in thread
From: Michael Wang @ 2012-07-23 2:30 UTC (permalink / raw)
To: Peter Zijlstra; +Cc: LKML, mingo, paul
On 07/21/2012 12:42 AM, Peter Zijlstra wrote:
> On Tue, 2012-07-17 at 17:03 +0800, Michael Wang wrote:
>> This patch set provide a way for user to dynamically configure the scheduler
>> domain flags, which usually to be static.
>
> NAK.. you don't get to expose all this nonsense in a 'stable' ABI.
>
> You shouldn't need to prod at them to begin with.
So is that means expose those domain flags to user is a bad idea at all?
Is this caused by that people don't need such feature or this feature
has do harm to kernel's stability?(it could be not...)
Regards,
Michael Wang
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^ permalink raw reply [flat|nested] 5+ messages in thread
* Re: [PATCH 0/5] cpusets: dynamical scheduler domain flags
2012-07-23 2:30 ` Michael Wang
@ 2012-07-23 4:28 ` Mike Galbraith
2012-07-23 4:58 ` Michael Wang
0 siblings, 1 reply; 5+ messages in thread
From: Mike Galbraith @ 2012-07-23 4:28 UTC (permalink / raw)
To: Michael Wang; +Cc: Peter Zijlstra, LKML, mingo, paul
On Mon, 2012-07-23 at 10:30 +0800, Michael Wang wrote:
> On 07/21/2012 12:42 AM, Peter Zijlstra wrote:
> > On Tue, 2012-07-17 at 17:03 +0800, Michael Wang wrote:
> >> This patch set provide a way for user to dynamically configure the scheduler
> >> domain flags, which usually to be static.
> >
> > NAK.. you don't get to expose all this nonsense in a 'stable' ABI.
> >
> > You shouldn't need to prod at them to begin with.
>
> So is that means expose those domain flags to user is a bad idea at all?
You can set/clear flags with scripts now, ie domain flags are already
exposed.. as defined by the running kernel.
SD_SHARE_PKG_RESOURCES is a good flag look at. What does flipping that
switch do, and what did it stop doing recently? So yeah, methinks
exporting flags via cpusets is a bad idea. Not only is existence of any
particular flag volatile, functionality behind it is volatile as well,
so having a button to poke does undefined things. (not to mention
non-exclusive sets)
-Mike
^ permalink raw reply [flat|nested] 5+ messages in thread
* Re: [PATCH 0/5] cpusets: dynamical scheduler domain flags
2012-07-23 4:28 ` Mike Galbraith
@ 2012-07-23 4:58 ` Michael Wang
0 siblings, 0 replies; 5+ messages in thread
From: Michael Wang @ 2012-07-23 4:58 UTC (permalink / raw)
To: Mike Galbraith; +Cc: Peter Zijlstra, LKML, mingo, paul
On 07/23/2012 12:28 PM, Mike Galbraith wrote:
> On Mon, 2012-07-23 at 10:30 +0800, Michael Wang wrote:
>> On 07/21/2012 12:42 AM, Peter Zijlstra wrote:
>>> On Tue, 2012-07-17 at 17:03 +0800, Michael Wang wrote:
>>>> This patch set provide a way for user to dynamically configure the scheduler
>>>> domain flags, which usually to be static.
>>>
>>> NAK.. you don't get to expose all this nonsense in a 'stable' ABI.
>>>
>>> You shouldn't need to prod at them to begin with.
>>
>> So is that means expose those domain flags to user is a bad idea at all?
>
> You can set/clear flags with scripts now, ie domain flags are already
> exposed.. as defined by the running kernel.
>
> SD_SHARE_PKG_RESOURCES is a good flag look at. What does flipping that
> switch do, and what did it stop doing recently? So yeah, methinks
> exporting flags via cpusets is a bad idea. Not only is existence of any
> particular flag volatile, functionality behind it is volatile as well,
> so having a button to poke does undefined things. (not to mention
> non-exclusive sets)
>
I think I got your and peter's opinion, so we could not make sure the
kernel could still work well if some flags was enabled because their
behave are always changing, and it's impossible to maintain such
volatile feature.
Actually I got this idea after reading:
http://marc.info/?l=linux-kernel&m=130822782111533
But looks like I don't get the point, so what we want is building the
domain according to some system topology designed by producer?
Regards,
Michael Wang
> -Mike
>
>
^ permalink raw reply [flat|nested] 5+ messages in thread
end of thread, other threads:[~2012-07-23 4:58 UTC | newest]
Thread overview: 5+ messages (download: mbox.gz / follow: Atom feed)
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2012-07-17 9:03 [PATCH 0/5] cpusets: dynamical scheduler domain flags Michael Wang
2012-07-20 16:42 ` Peter Zijlstra
2012-07-23 2:30 ` Michael Wang
2012-07-23 4:28 ` Mike Galbraith
2012-07-23 4:58 ` Michael Wang
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