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* [LTP] Regarding shmat01 syscall test
@ 2012-10-23  9:24 Om Prakash PAL
  2012-10-23  9:37 ` Wanlong Gao
  0 siblings, 1 reply; 12+ messages in thread
From: Om Prakash PAL @ 2012-10-23  9:24 UTC (permalink / raw)
  To: ltp-list


[-- Attachment #1.1: Type: text/plain, Size: 841 bytes --]

Hi,
I am working on syscall test:  shmat01.c
I have some confusion:

In setup() : it is  allocating shared memory by shmget() and then attaching by shmat() and after  that detaching the attached address (i.e. shmdt())

        if (shmdt((const void *)base_addr) == -1) {
                tst_brkm(TBROK, cleanup, "Couldn't detach shared memory");
        }

And again in main function it is using same "base_addr" as attaching address,

addr = shmat(*(TC[i].shmid), base_addr+TC[i].offset,
                                     TC[i].flags);
how can we ensure(100%) that base_addr (virtual) will be free till this point for attaching?.
there is possibility that this address(base_addr) will be used, so in that case this shmat() will fail.
Please correct me if I am wrong.
Thanks in advance.

Best Regards,
Om Prakash Pal

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* Re: [LTP] Regarding shmat01 syscall test
  2012-10-23  9:24 [LTP] Regarding shmat01 syscall test Om Prakash PAL
@ 2012-10-23  9:37 ` Wanlong Gao
  2012-10-23 10:05   ` Om Prakash PAL
  0 siblings, 1 reply; 12+ messages in thread
From: Wanlong Gao @ 2012-10-23  9:37 UTC (permalink / raw)
  To: Om Prakash PAL; +Cc: ltp-list

On 10/23/2012 05:24 PM, Om Prakash PAL wrote:
> Hi,
> 
> I am working on syscall test:  shmat01.c
> 
> I have some confusion:
> 
>  
> 
> In setup() : it is  allocating shared memory by shmget() and then attaching by shmat() and after  that detaching the attached address (i.e. shmdt())   
> 
>  
> 
>         if (shmdt((const void *)base_addr) == -1) {
> 
>                 tst_brkm(TBROK, cleanup, "Couldn't detach shared memory");
> 
>         }
> 
>  
> 
> And again in main function it is using same “base_addr” as attaching address,
> 
>  
> 
> addr = shmat(*(TC[i].shmid), base_addr+TC[i].offset,
> 
>                                      TC[i].flags);
> 
> how can we ensure(100%) that base_addr (virtual) will be free till this point for attaching?.

Maybe we can't, but I didn't see any fail on this. Did you see any testing failure here?

Thanks,
Wanlong Gao

> 
> there is possibility that this address(base_addr) will be used, so in that case this shmat() will fail.
> 
> Please correct me if I am wrong.
> 
> Thanks in advance.
> 
>  
> 
> Best Regards,
> 
> Om Prakash Pal   
> 
> 
> 
> ------------------------------------------------------------------------------
> Everyone hates slow websites. So do we.
> Make your web apps faster with AppDynamics
> Download AppDynamics Lite for free today:
> http://p.sf.net/sfu/appdyn_sfd2d_oct
> 
> 
> 
> _______________________________________________
> Ltp-list mailing list
> Ltp-list@lists.sourceforge.net
> https://lists.sourceforge.net/lists/listinfo/ltp-list
> 


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^ permalink raw reply	[flat|nested] 12+ messages in thread

* Re: [LTP] Regarding shmat01 syscall test
  2012-10-23  9:37 ` Wanlong Gao
@ 2012-10-23 10:05   ` Om Prakash PAL
  2012-10-24  0:45     ` Wanlong Gao
  0 siblings, 1 reply; 12+ messages in thread
From: Om Prakash PAL @ 2012-10-23 10:05 UTC (permalink / raw)
  To: gaowanlong; +Cc: ltp-list



-----Original Message-----
From: Wanlong Gao [mailto:gaowanlong@cn.fujitsu.com] 
Sent: Tuesday, October 23, 2012 3:07 PM
To: Om Prakash PAL
Cc: ltp-list@lists.sourceforge.net
Subject: Re: [LTP] Regarding shmat01 syscall test

On 10/23/2012 05:24 PM, Om Prakash PAL wrote:
> Hi,
> 
> I am working on syscall test:  shmat01.c
> 
> I have some confusion:
> 
>  
> 
> In setup() : it is  allocating shared memory by shmget() and then attaching by shmat() and after  that detaching the attached address (i.e. shmdt())   
> 
>  
> 
>         if (shmdt((const void *)base_addr) == -1) {
> 
>                 tst_brkm(TBROK, cleanup, "Couldn't detach shared memory");
> 
>         }
> 
>  
> 
> And again in main function it is using same "base_addr" as attaching address,
> 
>  
> 
> addr = shmat(*(TC[i].shmid), base_addr+TC[i].offset,
> 
>                                      TC[i].flags);
> 
> how can we ensure(100%) that base_addr (virtual) will be free till this point for attaching?.

Maybe we can't, but I didn't see any fail on this. Did you see any testing failure here?

Yes, I got some failure and the reason of failure is : the address at which we want to attach is busy.

Best Regards,
Om Prakash Pal  



Thanks,
Wanlong Gao

> 
> there is possibility that this address(base_addr) will be used, so in that case this shmat() will fail.
> 
> Please correct me if I am wrong.
> 
> Thanks in advance.
> 
>  
> 
> Best Regards,
> 
> Om Prakash Pal   
> 
> 
> 
> ------------------------------------------------------------------------------
> Everyone hates slow websites. So do we.
> Make your web apps faster with AppDynamics
> Download AppDynamics Lite for free today:
> http://p.sf.net/sfu/appdyn_sfd2d_oct
> 
> 
> 
> _______________________________________________
> Ltp-list mailing list
> Ltp-list@lists.sourceforge.net
> https://lists.sourceforge.net/lists/listinfo/ltp-list
> 


------------------------------------------------------------------------------
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^ permalink raw reply	[flat|nested] 12+ messages in thread

* Re: [LTP] Regarding shmat01 syscall test
  2012-10-23 10:05   ` Om Prakash PAL
@ 2012-10-24  0:45     ` Wanlong Gao
  2012-10-24  6:43       ` Jan Stancek
  0 siblings, 1 reply; 12+ messages in thread
From: Wanlong Gao @ 2012-10-24  0:45 UTC (permalink / raw)
  To: Om Prakash PAL; +Cc: ltp-list

On 10/23/2012 06:05 PM, Om Prakash PAL wrote:
> 
> 
> -----Original Message-----
> From: Wanlong Gao [mailto:gaowanlong@cn.fujitsu.com] 
> Sent: Tuesday, October 23, 2012 3:07 PM
> To: Om Prakash PAL
> Cc: ltp-list@lists.sourceforge.net
> Subject: Re: [LTP] Regarding shmat01 syscall test
> 
> On 10/23/2012 05:24 PM, Om Prakash PAL wrote:
>> Hi,
>>
>> I am working on syscall test:  shmat01.c
>>
>> I have some confusion:
>>
>>  
>>
>> In setup() : it is  allocating shared memory by shmget() and then attaching by shmat() and after  that detaching the attached address (i.e. shmdt())   
>>
>>  
>>
>>         if (shmdt((const void *)base_addr) == -1) {
>>
>>                 tst_brkm(TBROK, cleanup, "Couldn't detach shared memory");
>>
>>         }
>>
>>  
>>
>> And again in main function it is using same "base_addr" as attaching address,
>>
>>  
>>
>> addr = shmat(*(TC[i].shmid), base_addr+TC[i].offset,
>>
>>                                      TC[i].flags);
>>
>> how can we ensure(100%) that base_addr (virtual) will be free till this point for attaching?.
> 
> Maybe we can't, but I didn't see any fail on this. Did you see any testing failure here?
> 
> Yes, I got some failure and the reason of failure is : the address at which we want to attach is busy.

OK, please feel free to send a patch, or can you tell us how to reproduce it?

Thanks,
Wanlong Gao

> 
> Best Regards,
> Om Prakash Pal  
> 
> 
> 
> Thanks,
> Wanlong Gao
> 
>>
>> there is possibility that this address(base_addr) will be used, so in that case this shmat() will fail.
>>
>> Please correct me if I am wrong.
>>
>> Thanks in advance.
>>
>>  
>>
>> Best Regards,
>>
>> Om Prakash Pal   
>>
>>
>>
>> ------------------------------------------------------------------------------
>> Everyone hates slow websites. So do we.
>> Make your web apps faster with AppDynamics
>> Download AppDynamics Lite for free today:
>> http://p.sf.net/sfu/appdyn_sfd2d_oct
>>
>>
>>
>> _______________________________________________
>> Ltp-list mailing list
>> Ltp-list@lists.sourceforge.net
>> https://lists.sourceforge.net/lists/listinfo/ltp-list
>>
> 
> 


------------------------------------------------------------------------------
Everyone hates slow websites. So do we.
Make your web apps faster with AppDynamics
Download AppDynamics Lite for free today:
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_______________________________________________
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^ permalink raw reply	[flat|nested] 12+ messages in thread

* Re: [LTP] Regarding shmat01 syscall test
  2012-10-24  0:45     ` Wanlong Gao
@ 2012-10-24  6:43       ` Jan Stancek
  2012-10-24  7:03         ` Wanlong Gao
  0 siblings, 1 reply; 12+ messages in thread
From: Jan Stancek @ 2012-10-24  6:43 UTC (permalink / raw)
  To: gaowanlong; +Cc: ltp-list



----- Original Message -----
> From: "Wanlong Gao" <gaowanlong@cn.fujitsu.com>
> To: "Om Prakash PAL" <omprakash.pal@stericsson.com>
> Cc: ltp-list@lists.sourceforge.net
> Sent: Wednesday, 24 October, 2012 2:45:47 AM
> Subject: Re: [LTP] Regarding shmat01 syscall test
> 
> On 10/23/2012 06:05 PM, Om Prakash PAL wrote:
> > 
> > 
> > -----Original Message-----
> > From: Wanlong Gao [mailto:gaowanlong@cn.fujitsu.com]
> > Sent: Tuesday, October 23, 2012 3:07 PM
> > To: Om Prakash PAL
> > Cc: ltp-list@lists.sourceforge.net
> > Subject: Re: [LTP] Regarding shmat01 syscall test
> > 
> > On 10/23/2012 05:24 PM, Om Prakash PAL wrote:
> >> Hi,
> >>
> >> I am working on syscall test:  shmat01.c
> >>
> >> I have some confusion:
> >>
> >>  
> >>
> >> In setup() : it is  allocating shared memory by shmget() and then
> >> attaching by shmat() and after  that detaching the attached
> >> address (i.e. shmdt())
> >>
> >>  
> >>
> >>         if (shmdt((const void *)base_addr) == -1) {
> >>
> >>                 tst_brkm(TBROK, cleanup, "Couldn't detach shared
> >>                 memory");
> >>
> >>         }
> >>
> >>  
> >>
> >> And again in main function it is using same "base_addr" as
> >> attaching address,
> >>
> >>  
> >>
> >> addr = shmat(*(TC[i].shmid), base_addr+TC[i].offset,
> >>
> >>                                      TC[i].flags);
> >>
> >> how can we ensure(100%) that base_addr (virtual) will be free till
> >> this point for attaching?.
> > 
> > Maybe we can't, but I didn't see any fail on this. Did you see any
> > testing failure here?
> > 
> > Yes, I got some failure and the reason of failure is : the address
> > at which we want to attach is busy.
> 
> OK, please feel free to send a patch, or can you tell us how to
> reproduce it?

I recall I could reproduce it, if I added single printf:
http://article.gmane.org/gmane.linux.ltp/16480

Regards,
Jan

------------------------------------------------------------------------------
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Download AppDynamics Lite for free today:
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Ltp-list@lists.sourceforge.net
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^ permalink raw reply	[flat|nested] 12+ messages in thread

* Re: [LTP] Regarding shmat01 syscall test
  2012-10-24  6:43       ` Jan Stancek
@ 2012-10-24  7:03         ` Wanlong Gao
  2012-10-24  7:49           ` Jan Stancek
  0 siblings, 1 reply; 12+ messages in thread
From: Wanlong Gao @ 2012-10-24  7:03 UTC (permalink / raw)
  To: Jan Stancek; +Cc: ltp-list

On 10/24/2012 02:43 PM, Jan Stancek wrote:
> 
> 
> ----- Original Message -----
>> From: "Wanlong Gao" <gaowanlong@cn.fujitsu.com>
>> To: "Om Prakash PAL" <omprakash.pal@stericsson.com>
>> Cc: ltp-list@lists.sourceforge.net
>> Sent: Wednesday, 24 October, 2012 2:45:47 AM
>> Subject: Re: [LTP] Regarding shmat01 syscall test
>>
>> On 10/23/2012 06:05 PM, Om Prakash PAL wrote:
>>>
>>>
>>> -----Original Message-----
>>> From: Wanlong Gao [mailto:gaowanlong@cn.fujitsu.com]
>>> Sent: Tuesday, October 23, 2012 3:07 PM
>>> To: Om Prakash PAL
>>> Cc: ltp-list@lists.sourceforge.net
>>> Subject: Re: [LTP] Regarding shmat01 syscall test
>>>
>>> On 10/23/2012 05:24 PM, Om Prakash PAL wrote:
>>>> Hi,
>>>>
>>>> I am working on syscall test:  shmat01.c
>>>>
>>>> I have some confusion:
>>>>
>>>>  
>>>>
>>>> In setup() : it is  allocating shared memory by shmget() and then
>>>> attaching by shmat() and after  that detaching the attached
>>>> address (i.e. shmdt())
>>>>
>>>>  
>>>>
>>>>         if (shmdt((const void *)base_addr) == -1) {
>>>>
>>>>                 tst_brkm(TBROK, cleanup, "Couldn't detach shared
>>>>                 memory");
>>>>
>>>>         }
>>>>
>>>>  
>>>>
>>>> And again in main function it is using same "base_addr" as
>>>> attaching address,
>>>>
>>>>  
>>>>
>>>> addr = shmat(*(TC[i].shmid), base_addr+TC[i].offset,
>>>>
>>>>                                      TC[i].flags);
>>>>
>>>> how can we ensure(100%) that base_addr (virtual) will be free till
>>>> this point for attaching?.
>>>
>>> Maybe we can't, but I didn't see any fail on this. Did you see any
>>> testing failure here?
>>>
>>> Yes, I got some failure and the reason of failure is : the address
>>> at which we want to attach is busy.
>>
>> OK, please feel free to send a patch, or can you tell us how to
>> reproduce it?
> 
> I recall I could reproduce it, if I added single printf:
> http://article.gmane.org/gmane.linux.ltp/16480

Do you get a solution? Send out a patch?


Thanks,
Wanlong Gao

> 
> Regards,
> Jan
> 


------------------------------------------------------------------------------
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Make your web apps faster with AppDynamics
Download AppDynamics Lite for free today:
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Ltp-list@lists.sourceforge.net
https://lists.sourceforge.net/lists/listinfo/ltp-list

^ permalink raw reply	[flat|nested] 12+ messages in thread

* Re: [LTP] Regarding shmat01 syscall test
  2012-10-24  7:03         ` Wanlong Gao
@ 2012-10-24  7:49           ` Jan Stancek
  2012-10-24  7:51             ` Wanlong Gao
  0 siblings, 1 reply; 12+ messages in thread
From: Jan Stancek @ 2012-10-24  7:49 UTC (permalink / raw)
  To: gaowanlong; +Cc: ltp-list



----- Original Message -----
> From: "Wanlong Gao" <gaowanlong@cn.fujitsu.com>
> To: "Jan Stancek" <jstancek@redhat.com>
> Cc: ltp-list@lists.sourceforge.net, "Om Prakash PAL" <omprakash.pal@stericsson.com>
> Sent: Wednesday, 24 October, 2012 9:03:16 AM
> Subject: Re: [LTP] Regarding shmat01 syscall test
> 
> On 10/24/2012 02:43 PM, Jan Stancek wrote:
> > 
> > 
> > ----- Original Message -----
> >> From: "Wanlong Gao" <gaowanlong@cn.fujitsu.com>
> >> To: "Om Prakash PAL" <omprakash.pal@stericsson.com>
> >> Cc: ltp-list@lists.sourceforge.net
> >> Sent: Wednesday, 24 October, 2012 2:45:47 AM
> >> Subject: Re: [LTP] Regarding shmat01 syscall test
> >>
> >> On 10/23/2012 06:05 PM, Om Prakash PAL wrote:
> >>>
> >>>
> >>> -----Original Message-----
> >>> From: Wanlong Gao [mailto:gaowanlong@cn.fujitsu.com]
> >>> Sent: Tuesday, October 23, 2012 3:07 PM
> >>> To: Om Prakash PAL
> >>> Cc: ltp-list@lists.sourceforge.net
> >>> Subject: Re: [LTP] Regarding shmat01 syscall test
> >>>
> >>> On 10/23/2012 05:24 PM, Om Prakash PAL wrote:
> >>>> Hi,
> >>>>
> >>>> I am working on syscall test:  shmat01.c
> >>>>
> >>>> I have some confusion:
> >>>>
> >>>>  
> >>>>
> >>>> In setup() : it is  allocating shared memory by shmget() and
> >>>> then
> >>>> attaching by shmat() and after  that detaching the attached
> >>>> address (i.e. shmdt())
> >>>>
> >>>>  
> >>>>
> >>>>         if (shmdt((const void *)base_addr) == -1) {
> >>>>
> >>>>                 tst_brkm(TBROK, cleanup, "Couldn't detach shared
> >>>>                 memory");
> >>>>
> >>>>         }
> >>>>
> >>>>  
> >>>>
> >>>> And again in main function it is using same "base_addr" as
> >>>> attaching address,
> >>>>
> >>>>  
> >>>>
> >>>> addr = shmat(*(TC[i].shmid), base_addr+TC[i].offset,
> >>>>
> >>>>                                      TC[i].flags);
> >>>>
> >>>> how can we ensure(100%) that base_addr (virtual) will be free
> >>>> till
> >>>> this point for attaching?.
> >>>
> >>> Maybe we can't, but I didn't see any fail on this. Did you see
> >>> any
> >>> testing failure here?
> >>>
> >>> Yes, I got some failure and the reason of failure is : the
> >>> address
> >>> at which we want to attach is busy.
> >>
> >> OK, please feel free to send a patch, or can you tell us how to
> >> reproduce it?
> > 
> > I recall I could reproduce it, if I added single printf:
> > http://article.gmane.org/gmane.linux.ltp/16480
> 
> Do you get a solution? Send out a patch?

No, I haven't send any patch.

About solution:
I'm thinking, that instead of probing with shmat, we can mmap large chunk of memory,
and then set base_addr somewhere in the middle and unmap the chunk.
That is, using address that get_unmapped_area() is unlikely to pick.

Regards,
Jan

> 
> 
> Thanks,
> Wanlong Gao
> 
> > 
> > Regards,
> > Jan
> > 
> 
> 

------------------------------------------------------------------------------
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^ permalink raw reply	[flat|nested] 12+ messages in thread

* Re: [LTP] Regarding shmat01 syscall test
  2012-10-24  7:49           ` Jan Stancek
@ 2012-10-24  7:51             ` Wanlong Gao
  2012-10-24  8:20               ` Jan Stancek
  0 siblings, 1 reply; 12+ messages in thread
From: Wanlong Gao @ 2012-10-24  7:51 UTC (permalink / raw)
  To: Jan Stancek; +Cc: ltp-list

On 10/24/2012 03:49 PM, Jan Stancek wrote:
> 
> 
> ----- Original Message -----
>> From: "Wanlong Gao" <gaowanlong@cn.fujitsu.com>
>> To: "Jan Stancek" <jstancek@redhat.com>
>> Cc: ltp-list@lists.sourceforge.net, "Om Prakash PAL" <omprakash.pal@stericsson.com>
>> Sent: Wednesday, 24 October, 2012 9:03:16 AM
>> Subject: Re: [LTP] Regarding shmat01 syscall test
>>
>> On 10/24/2012 02:43 PM, Jan Stancek wrote:
>>>
>>>
>>> ----- Original Message -----
>>>> From: "Wanlong Gao" <gaowanlong@cn.fujitsu.com>
>>>> To: "Om Prakash PAL" <omprakash.pal@stericsson.com>
>>>> Cc: ltp-list@lists.sourceforge.net
>>>> Sent: Wednesday, 24 October, 2012 2:45:47 AM
>>>> Subject: Re: [LTP] Regarding shmat01 syscall test
>>>>
>>>> On 10/23/2012 06:05 PM, Om Prakash PAL wrote:
>>>>>
>>>>>
>>>>> -----Original Message-----
>>>>> From: Wanlong Gao [mailto:gaowanlong@cn.fujitsu.com]
>>>>> Sent: Tuesday, October 23, 2012 3:07 PM
>>>>> To: Om Prakash PAL
>>>>> Cc: ltp-list@lists.sourceforge.net
>>>>> Subject: Re: [LTP] Regarding shmat01 syscall test
>>>>>
>>>>> On 10/23/2012 05:24 PM, Om Prakash PAL wrote:
>>>>>> Hi,
>>>>>>
>>>>>> I am working on syscall test:  shmat01.c
>>>>>>
>>>>>> I have some confusion:
>>>>>>
>>>>>>  
>>>>>>
>>>>>> In setup() : it is  allocating shared memory by shmget() and
>>>>>> then
>>>>>> attaching by shmat() and after  that detaching the attached
>>>>>> address (i.e. shmdt())
>>>>>>
>>>>>>  
>>>>>>
>>>>>>         if (shmdt((const void *)base_addr) == -1) {
>>>>>>
>>>>>>                 tst_brkm(TBROK, cleanup, "Couldn't detach shared
>>>>>>                 memory");
>>>>>>
>>>>>>         }
>>>>>>
>>>>>>  
>>>>>>
>>>>>> And again in main function it is using same "base_addr" as
>>>>>> attaching address,
>>>>>>
>>>>>>  
>>>>>>
>>>>>> addr = shmat(*(TC[i].shmid), base_addr+TC[i].offset,
>>>>>>
>>>>>>                                      TC[i].flags);
>>>>>>
>>>>>> how can we ensure(100%) that base_addr (virtual) will be free
>>>>>> till
>>>>>> this point for attaching?.
>>>>>
>>>>> Maybe we can't, but I didn't see any fail on this. Did you see
>>>>> any
>>>>> testing failure here?
>>>>>
>>>>> Yes, I got some failure and the reason of failure is : the
>>>>> address
>>>>> at which we want to attach is busy.
>>>>
>>>> OK, please feel free to send a patch, or can you tell us how to
>>>> reproduce it?
>>>
>>> I recall I could reproduce it, if I added single printf:
>>> http://article.gmane.org/gmane.linux.ltp/16480
>>
>> Do you get a solution? Send out a patch?
> 
> No, I haven't send any patch.
> 
> About solution:
> I'm thinking, that instead of probing with shmat, we can mmap large chunk of memory,
> and then set base_addr somewhere in the middle and unmap the chunk.
> That is, using address that get_unmapped_area() is unlikely to pick.

This idea seems good, bug how can you decide the size of this "chunk of memory"?

Thanks,
Wanlong Gao

> 
> Regards,
> Jan
> 
>>
>>
>> Thanks,
>> Wanlong Gao
>>
>>>
>>> Regards,
>>> Jan
>>>
>>
>>
> 


------------------------------------------------------------------------------
Everyone hates slow websites. So do we.
Make your web apps faster with AppDynamics
Download AppDynamics Lite for free today:
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_______________________________________________
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Ltp-list@lists.sourceforge.net
https://lists.sourceforge.net/lists/listinfo/ltp-list

^ permalink raw reply	[flat|nested] 12+ messages in thread

* Re: [LTP] Regarding shmat01 syscall test
  2012-10-24  7:51             ` Wanlong Gao
@ 2012-10-24  8:20               ` Jan Stancek
  2012-10-26  1:45                 ` Wanlong Gao
  0 siblings, 1 reply; 12+ messages in thread
From: Jan Stancek @ 2012-10-24  8:20 UTC (permalink / raw)
  To: gaowanlong; +Cc: ltp-list



----- Original Message -----
> From: "Wanlong Gao" <gaowanlong@cn.fujitsu.com>
> To: "Jan Stancek" <jstancek@redhat.com>
> Cc: ltp-list@lists.sourceforge.net, "Om Prakash PAL" <omprakash.pal@stericsson.com>
> Sent: Wednesday, 24 October, 2012 9:51:59 AM
> Subject: Re: [LTP] Regarding shmat01 syscall test
> 
> On 10/24/2012 03:49 PM, Jan Stancek wrote:
> > 
> > 
> > ----- Original Message -----
> >> From: "Wanlong Gao" <gaowanlong@cn.fujitsu.com>
> >> To: "Jan Stancek" <jstancek@redhat.com>
> >> Cc: ltp-list@lists.sourceforge.net, "Om Prakash PAL"
> >> <omprakash.pal@stericsson.com>
> >> Sent: Wednesday, 24 October, 2012 9:03:16 AM
> >> Subject: Re: [LTP] Regarding shmat01 syscall test
> >>
> >> On 10/24/2012 02:43 PM, Jan Stancek wrote:
> >>>
> >>>
> >>> ----- Original Message -----
> >>>> From: "Wanlong Gao" <gaowanlong@cn.fujitsu.com>
> >>>> To: "Om Prakash PAL" <omprakash.pal@stericsson.com>
> >>>> Cc: ltp-list@lists.sourceforge.net
> >>>> Sent: Wednesday, 24 October, 2012 2:45:47 AM
> >>>> Subject: Re: [LTP] Regarding shmat01 syscall test
> >>>>
> >>>> On 10/23/2012 06:05 PM, Om Prakash PAL wrote:
> >>>>>
> >>>>>
> >>>>> -----Original Message-----
> >>>>> From: Wanlong Gao [mailto:gaowanlong@cn.fujitsu.com]
> >>>>> Sent: Tuesday, October 23, 2012 3:07 PM
> >>>>> To: Om Prakash PAL
> >>>>> Cc: ltp-list@lists.sourceforge.net
> >>>>> Subject: Re: [LTP] Regarding shmat01 syscall test
> >>>>>
> >>>>> On 10/23/2012 05:24 PM, Om Prakash PAL wrote:
> >>>>>> Hi,
> >>>>>>
> >>>>>> I am working on syscall test:  shmat01.c
> >>>>>>
> >>>>>> I have some confusion:
> >>>>>>
> >>>>>>  
> >>>>>>
> >>>>>> In setup() : it is  allocating shared memory by shmget() and
> >>>>>> then
> >>>>>> attaching by shmat() and after  that detaching the attached
> >>>>>> address (i.e. shmdt())
> >>>>>>
> >>>>>>  
> >>>>>>
> >>>>>>         if (shmdt((const void *)base_addr) == -1) {
> >>>>>>
> >>>>>>                 tst_brkm(TBROK, cleanup, "Couldn't detach
> >>>>>>                 shared
> >>>>>>                 memory");
> >>>>>>
> >>>>>>         }
> >>>>>>
> >>>>>>  
> >>>>>>
> >>>>>> And again in main function it is using same "base_addr" as
> >>>>>> attaching address,
> >>>>>>
> >>>>>>  
> >>>>>>
> >>>>>> addr = shmat(*(TC[i].shmid), base_addr+TC[i].offset,
> >>>>>>
> >>>>>>                                      TC[i].flags);
> >>>>>>
> >>>>>> how can we ensure(100%) that base_addr (virtual) will be free
> >>>>>> till
> >>>>>> this point for attaching?.
> >>>>>
> >>>>> Maybe we can't, but I didn't see any fail on this. Did you see
> >>>>> any
> >>>>> testing failure here?
> >>>>>
> >>>>> Yes, I got some failure and the reason of failure is : the
> >>>>> address
> >>>>> at which we want to attach is busy.
> >>>>
> >>>> OK, please feel free to send a patch, or can you tell us how to
> >>>> reproduce it?
> >>>
> >>> I recall I could reproduce it, if I added single printf:
> >>> http://article.gmane.org/gmane.linux.ltp/16480
> >>
> >> Do you get a solution? Send out a patch?
> > 
> > No, I haven't send any patch.
> > 
> > About solution:
> > I'm thinking, that instead of probing with shmat, we can mmap large
> > chunk of memory,
> > and then set base_addr somewhere in the middle and unmap the chunk.
> > That is, using address that get_unmapped_area() is unlikely to
> > pick.
> 
> This idea seems good, bug how can you decide the size of this "chunk
> of memory"?

Good question. How about starting with some large value, say 512M,
and keep dividing by 2 until mmap succeeds?

Regards,
Jan

> 
> Thanks,
> Wanlong Gao
> 
> > 
> > Regards,
> > Jan
> > 
> >>
> >>
> >> Thanks,
> >> Wanlong Gao
> >>
> >>>
> >>> Regards,
> >>> Jan
> >>>
> >>
> >>
> > 
> 
> 

------------------------------------------------------------------------------
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^ permalink raw reply	[flat|nested] 12+ messages in thread

* Re: [LTP] Regarding shmat01 syscall test
  2012-10-24  8:20               ` Jan Stancek
@ 2012-10-26  1:45                 ` Wanlong Gao
  2012-10-26  8:01                   ` Jan Stancek
  0 siblings, 1 reply; 12+ messages in thread
From: Wanlong Gao @ 2012-10-26  1:45 UTC (permalink / raw)
  To: Jan Stancek; +Cc: ltp-list

On 10/24/2012 04:20 PM, Jan Stancek wrote:
> 
> 
> ----- Original Message -----
>> From: "Wanlong Gao" <gaowanlong@cn.fujitsu.com>
>> To: "Jan Stancek" <jstancek@redhat.com>
>> Cc: ltp-list@lists.sourceforge.net, "Om Prakash PAL" <omprakash.pal@stericsson.com>
>> Sent: Wednesday, 24 October, 2012 9:51:59 AM
>> Subject: Re: [LTP] Regarding shmat01 syscall test
>>
>> On 10/24/2012 03:49 PM, Jan Stancek wrote:
>>>
>>>
>>> ----- Original Message -----
>>>> From: "Wanlong Gao" <gaowanlong@cn.fujitsu.com>
>>>> To: "Jan Stancek" <jstancek@redhat.com>
>>>> Cc: ltp-list@lists.sourceforge.net, "Om Prakash PAL"
>>>> <omprakash.pal@stericsson.com>
>>>> Sent: Wednesday, 24 October, 2012 9:03:16 AM
>>>> Subject: Re: [LTP] Regarding shmat01 syscall test
>>>>
>>>> On 10/24/2012 02:43 PM, Jan Stancek wrote:
>>>>>
>>>>>
>>>>> ----- Original Message -----
>>>>>> From: "Wanlong Gao" <gaowanlong@cn.fujitsu.com>
>>>>>> To: "Om Prakash PAL" <omprakash.pal@stericsson.com>
>>>>>> Cc: ltp-list@lists.sourceforge.net
>>>>>> Sent: Wednesday, 24 October, 2012 2:45:47 AM
>>>>>> Subject: Re: [LTP] Regarding shmat01 syscall test
>>>>>>
>>>>>> On 10/23/2012 06:05 PM, Om Prakash PAL wrote:
>>>>>>>
>>>>>>>
>>>>>>> -----Original Message-----
>>>>>>> From: Wanlong Gao [mailto:gaowanlong@cn.fujitsu.com]
>>>>>>> Sent: Tuesday, October 23, 2012 3:07 PM
>>>>>>> To: Om Prakash PAL
>>>>>>> Cc: ltp-list@lists.sourceforge.net
>>>>>>> Subject: Re: [LTP] Regarding shmat01 syscall test
>>>>>>>
>>>>>>> On 10/23/2012 05:24 PM, Om Prakash PAL wrote:
>>>>>>>> Hi,
>>>>>>>>
>>>>>>>> I am working on syscall test:  shmat01.c
>>>>>>>>
>>>>>>>> I have some confusion:
>>>>>>>>
>>>>>>>>  
>>>>>>>>
>>>>>>>> In setup() : it is  allocating shared memory by shmget() and
>>>>>>>> then
>>>>>>>> attaching by shmat() and after  that detaching the attached
>>>>>>>> address (i.e. shmdt())
>>>>>>>>
>>>>>>>>  
>>>>>>>>
>>>>>>>>         if (shmdt((const void *)base_addr) == -1) {
>>>>>>>>
>>>>>>>>                 tst_brkm(TBROK, cleanup, "Couldn't detach
>>>>>>>>                 shared
>>>>>>>>                 memory");
>>>>>>>>
>>>>>>>>         }
>>>>>>>>
>>>>>>>>  
>>>>>>>>
>>>>>>>> And again in main function it is using same "base_addr" as
>>>>>>>> attaching address,
>>>>>>>>
>>>>>>>>  
>>>>>>>>
>>>>>>>> addr = shmat(*(TC[i].shmid), base_addr+TC[i].offset,
>>>>>>>>
>>>>>>>>                                      TC[i].flags);
>>>>>>>>
>>>>>>>> how can we ensure(100%) that base_addr (virtual) will be free
>>>>>>>> till
>>>>>>>> this point for attaching?.
>>>>>>>
>>>>>>> Maybe we can't, but I didn't see any fail on this. Did you see
>>>>>>> any
>>>>>>> testing failure here?
>>>>>>>
>>>>>>> Yes, I got some failure and the reason of failure is : the
>>>>>>> address
>>>>>>> at which we want to attach is busy.
>>>>>>
>>>>>> OK, please feel free to send a patch, or can you tell us how to
>>>>>> reproduce it?
>>>>>
>>>>> I recall I could reproduce it, if I added single printf:
>>>>> http://article.gmane.org/gmane.linux.ltp/16480
>>>>
>>>> Do you get a solution? Send out a patch?
>>>
>>> No, I haven't send any patch.
>>>
>>> About solution:
>>> I'm thinking, that instead of probing with shmat, we can mmap large
>>> chunk of memory,
>>> and then set base_addr somewhere in the middle and unmap the chunk.
>>> That is, using address that get_unmapped_area() is unlikely to
>>> pick.
>>
>> This idea seems good, bug how can you decide the size of this "chunk
>> of memory"?
> 
> Good question. How about starting with some large value, say 512M,
> and keep dividing by 2 until mmap succeeds?

So, can you send out a patch to see if others have an objection?

Thanks,
Wanlong Gao

> 
> Regards,
> Jan
> 
>>
>> Thanks,
>> Wanlong Gao
>>
>>>
>>> Regards,
>>> Jan
>>>
>>>>
>>>>
>>>> Thanks,
>>>> Wanlong Gao
>>>>
>>>>>
>>>>> Regards,
>>>>> Jan
>>>>>
>>>>
>>>>
>>>
>>
>>
> 


------------------------------------------------------------------------------
Everyone hates slow websites. So do we.
Make your web apps faster with AppDynamics
Download AppDynamics Lite for free today:
http://p.sf.net/sfu/appdyn_sfd2d_oct
_______________________________________________
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Ltp-list@lists.sourceforge.net
https://lists.sourceforge.net/lists/listinfo/ltp-list

^ permalink raw reply	[flat|nested] 12+ messages in thread

* Re: [LTP] Regarding shmat01 syscall test
  2012-10-26  1:45                 ` Wanlong Gao
@ 2012-10-26  8:01                   ` Jan Stancek
  2012-10-26  8:03                     ` Wanlong Gao
  0 siblings, 1 reply; 12+ messages in thread
From: Jan Stancek @ 2012-10-26  8:01 UTC (permalink / raw)
  To: gaowanlong; +Cc: ltp-list



----- Original Message -----
> From: "Wanlong Gao" <gaowanlong@cn.fujitsu.com>
> To: "Jan Stancek" <jstancek@redhat.com>
> Cc: ltp-list@lists.sourceforge.net, "Om Prakash PAL" <omprakash.pal@stericsson.com>
> Sent: Friday, 26 October, 2012 3:45:31 AM
> Subject: Re: [LTP] Regarding shmat01 syscall test
> 
> On 10/24/2012 04:20 PM, Jan Stancek wrote:
> > 
> > 
> > ----- Original Message -----
> >> From: "Wanlong Gao" <gaowanlong@cn.fujitsu.com>
> >> To: "Jan Stancek" <jstancek@redhat.com>
> >> Cc: ltp-list@lists.sourceforge.net, "Om Prakash PAL"
> >> <omprakash.pal@stericsson.com>
> >> Sent: Wednesday, 24 October, 2012 9:51:59 AM
> >> Subject: Re: [LTP] Regarding shmat01 syscall test
> >>
> >> On 10/24/2012 03:49 PM, Jan Stancek wrote:
> >>>
> >>>
> >>> ----- Original Message -----
> >>>> From: "Wanlong Gao" <gaowanlong@cn.fujitsu.com>
> >>>> To: "Jan Stancek" <jstancek@redhat.com>
> >>>> Cc: ltp-list@lists.sourceforge.net, "Om Prakash PAL"
> >>>> <omprakash.pal@stericsson.com>
> >>>> Sent: Wednesday, 24 October, 2012 9:03:16 AM
> >>>> Subject: Re: [LTP] Regarding shmat01 syscall test
> >>>>
> >>>> On 10/24/2012 02:43 PM, Jan Stancek wrote:
> >>>>>
> >>>>>
> >>>>> ----- Original Message -----
> >>>>>> From: "Wanlong Gao" <gaowanlong@cn.fujitsu.com>
> >>>>>> To: "Om Prakash PAL" <omprakash.pal@stericsson.com>
> >>>>>> Cc: ltp-list@lists.sourceforge.net
> >>>>>> Sent: Wednesday, 24 October, 2012 2:45:47 AM
> >>>>>> Subject: Re: [LTP] Regarding shmat01 syscall test
> >>>>>>
> >>>>>> On 10/23/2012 06:05 PM, Om Prakash PAL wrote:
> >>>>>>>
> >>>>>>>
> >>>>>>> -----Original Message-----
> >>>>>>> From: Wanlong Gao [mailto:gaowanlong@cn.fujitsu.com]
> >>>>>>> Sent: Tuesday, October 23, 2012 3:07 PM
> >>>>>>> To: Om Prakash PAL
> >>>>>>> Cc: ltp-list@lists.sourceforge.net
> >>>>>>> Subject: Re: [LTP] Regarding shmat01 syscall test
> >>>>>>>
> >>>>>>> On 10/23/2012 05:24 PM, Om Prakash PAL wrote:
> >>>>>>>> Hi,
> >>>>>>>>
> >>>>>>>> I am working on syscall test:  shmat01.c
> >>>>>>>>
> >>>>>>>> I have some confusion:
> >>>>>>>>
> >>>>>>>>  
> >>>>>>>>
> >>>>>>>> In setup() : it is  allocating shared memory by shmget() and
> >>>>>>>> then
> >>>>>>>> attaching by shmat() and after  that detaching the attached
> >>>>>>>> address (i.e. shmdt())
> >>>>>>>>
> >>>>>>>>  
> >>>>>>>>
> >>>>>>>>         if (shmdt((const void *)base_addr) == -1) {
> >>>>>>>>
> >>>>>>>>                 tst_brkm(TBROK, cleanup, "Couldn't detach
> >>>>>>>>                 shared
> >>>>>>>>                 memory");
> >>>>>>>>
> >>>>>>>>         }
> >>>>>>>>
> >>>>>>>>  
> >>>>>>>>
> >>>>>>>> And again in main function it is using same "base_addr" as
> >>>>>>>> attaching address,
> >>>>>>>>
> >>>>>>>>  
> >>>>>>>>
> >>>>>>>> addr = shmat(*(TC[i].shmid), base_addr+TC[i].offset,
> >>>>>>>>
> >>>>>>>>                                      TC[i].flags);
> >>>>>>>>
> >>>>>>>> how can we ensure(100%) that base_addr (virtual) will be
> >>>>>>>> free
> >>>>>>>> till
> >>>>>>>> this point for attaching?.
> >>>>>>>
> >>>>>>> Maybe we can't, but I didn't see any fail on this. Did you
> >>>>>>> see
> >>>>>>> any
> >>>>>>> testing failure here?
> >>>>>>>
> >>>>>>> Yes, I got some failure and the reason of failure is : the
> >>>>>>> address
> >>>>>>> at which we want to attach is busy.
> >>>>>>
> >>>>>> OK, please feel free to send a patch, or can you tell us how
> >>>>>> to
> >>>>>> reproduce it?
> >>>>>
> >>>>> I recall I could reproduce it, if I added single printf:
> >>>>> http://article.gmane.org/gmane.linux.ltp/16480
> >>>>
> >>>> Do you get a solution? Send out a patch?
> >>>
> >>> No, I haven't send any patch.
> >>>
> >>> About solution:
> >>> I'm thinking, that instead of probing with shmat, we can mmap
> >>> large
> >>> chunk of memory,
> >>> and then set base_addr somewhere in the middle and unmap the
> >>> chunk.
> >>> That is, using address that get_unmapped_area() is unlikely to
> >>> pick.
> >>
> >> This idea seems good, bug how can you decide the size of this
> >> "chunk
> >> of memory"?
> > 
> > Good question. How about starting with some large value, say 512M,
> > and keep dividing by 2 until mmap succeeds?
> 
> So, can you send out a patch to see if others have an objection?

Sure, I'll have a look at this today.

Regards,
Jan

------------------------------------------------------------------------------
Everyone hates slow websites. So do we.
Make your web apps faster with AppDynamics
Download AppDynamics Lite for free today:
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_______________________________________________
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^ permalink raw reply	[flat|nested] 12+ messages in thread

* Re: [LTP] Regarding shmat01 syscall test
  2012-10-26  8:01                   ` Jan Stancek
@ 2012-10-26  8:03                     ` Wanlong Gao
  0 siblings, 0 replies; 12+ messages in thread
From: Wanlong Gao @ 2012-10-26  8:03 UTC (permalink / raw)
  To: Jan Stancek; +Cc: ltp-list

On 10/26/2012 04:01 PM, Jan Stancek wrote:
> 
> 
> ----- Original Message -----
>> From: "Wanlong Gao" <gaowanlong@cn.fujitsu.com>
>> To: "Jan Stancek" <jstancek@redhat.com>
>> Cc: ltp-list@lists.sourceforge.net, "Om Prakash PAL" <omprakash.pal@stericsson.com>
>> Sent: Friday, 26 October, 2012 3:45:31 AM
>> Subject: Re: [LTP] Regarding shmat01 syscall test
>>
>> On 10/24/2012 04:20 PM, Jan Stancek wrote:
>>>
>>>
>>> ----- Original Message -----
>>>> From: "Wanlong Gao" <gaowanlong@cn.fujitsu.com>
>>>> To: "Jan Stancek" <jstancek@redhat.com>
>>>> Cc: ltp-list@lists.sourceforge.net, "Om Prakash PAL"
>>>> <omprakash.pal@stericsson.com>
>>>> Sent: Wednesday, 24 October, 2012 9:51:59 AM
>>>> Subject: Re: [LTP] Regarding shmat01 syscall test
>>>>
>>>> On 10/24/2012 03:49 PM, Jan Stancek wrote:
>>>>>
>>>>>
>>>>> ----- Original Message -----
>>>>>> From: "Wanlong Gao" <gaowanlong@cn.fujitsu.com>
>>>>>> To: "Jan Stancek" <jstancek@redhat.com>
>>>>>> Cc: ltp-list@lists.sourceforge.net, "Om Prakash PAL"
>>>>>> <omprakash.pal@stericsson.com>
>>>>>> Sent: Wednesday, 24 October, 2012 9:03:16 AM
>>>>>> Subject: Re: [LTP] Regarding shmat01 syscall test
>>>>>>
>>>>>> On 10/24/2012 02:43 PM, Jan Stancek wrote:
>>>>>>>
>>>>>>>
>>>>>>> ----- Original Message -----
>>>>>>>> From: "Wanlong Gao" <gaowanlong@cn.fujitsu.com>
>>>>>>>> To: "Om Prakash PAL" <omprakash.pal@stericsson.com>
>>>>>>>> Cc: ltp-list@lists.sourceforge.net
>>>>>>>> Sent: Wednesday, 24 October, 2012 2:45:47 AM
>>>>>>>> Subject: Re: [LTP] Regarding shmat01 syscall test
>>>>>>>>
>>>>>>>> On 10/23/2012 06:05 PM, Om Prakash PAL wrote:
>>>>>>>>>
>>>>>>>>>
>>>>>>>>> -----Original Message-----
>>>>>>>>> From: Wanlong Gao [mailto:gaowanlong@cn.fujitsu.com]
>>>>>>>>> Sent: Tuesday, October 23, 2012 3:07 PM
>>>>>>>>> To: Om Prakash PAL
>>>>>>>>> Cc: ltp-list@lists.sourceforge.net
>>>>>>>>> Subject: Re: [LTP] Regarding shmat01 syscall test
>>>>>>>>>
>>>>>>>>> On 10/23/2012 05:24 PM, Om Prakash PAL wrote:
>>>>>>>>>> Hi,
>>>>>>>>>>
>>>>>>>>>> I am working on syscall test:  shmat01.c
>>>>>>>>>>
>>>>>>>>>> I have some confusion:
>>>>>>>>>>
>>>>>>>>>>  
>>>>>>>>>>
>>>>>>>>>> In setup() : it is  allocating shared memory by shmget() and
>>>>>>>>>> then
>>>>>>>>>> attaching by shmat() and after  that detaching the attached
>>>>>>>>>> address (i.e. shmdt())
>>>>>>>>>>
>>>>>>>>>>  
>>>>>>>>>>
>>>>>>>>>>         if (shmdt((const void *)base_addr) == -1) {
>>>>>>>>>>
>>>>>>>>>>                 tst_brkm(TBROK, cleanup, "Couldn't detach
>>>>>>>>>>                 shared
>>>>>>>>>>                 memory");
>>>>>>>>>>
>>>>>>>>>>         }
>>>>>>>>>>
>>>>>>>>>>  
>>>>>>>>>>
>>>>>>>>>> And again in main function it is using same "base_addr" as
>>>>>>>>>> attaching address,
>>>>>>>>>>
>>>>>>>>>>  
>>>>>>>>>>
>>>>>>>>>> addr = shmat(*(TC[i].shmid), base_addr+TC[i].offset,
>>>>>>>>>>
>>>>>>>>>>                                      TC[i].flags);
>>>>>>>>>>
>>>>>>>>>> how can we ensure(100%) that base_addr (virtual) will be
>>>>>>>>>> free
>>>>>>>>>> till
>>>>>>>>>> this point for attaching?.
>>>>>>>>>
>>>>>>>>> Maybe we can't, but I didn't see any fail on this. Did you
>>>>>>>>> see
>>>>>>>>> any
>>>>>>>>> testing failure here?
>>>>>>>>>
>>>>>>>>> Yes, I got some failure and the reason of failure is : the
>>>>>>>>> address
>>>>>>>>> at which we want to attach is busy.
>>>>>>>>
>>>>>>>> OK, please feel free to send a patch, or can you tell us how
>>>>>>>> to
>>>>>>>> reproduce it?
>>>>>>>
>>>>>>> I recall I could reproduce it, if I added single printf:
>>>>>>> http://article.gmane.org/gmane.linux.ltp/16480
>>>>>>
>>>>>> Do you get a solution? Send out a patch?
>>>>>
>>>>> No, I haven't send any patch.
>>>>>
>>>>> About solution:
>>>>> I'm thinking, that instead of probing with shmat, we can mmap
>>>>> large
>>>>> chunk of memory,
>>>>> and then set base_addr somewhere in the middle and unmap the
>>>>> chunk.
>>>>> That is, using address that get_unmapped_area() is unlikely to
>>>>> pick.
>>>>
>>>> This idea seems good, bug how can you decide the size of this
>>>> "chunk
>>>> of memory"?
>>>
>>> Good question. How about starting with some large value, say 512M,
>>> and keep dividing by 2 until mmap succeeds?
>>
>> So, can you send out a patch to see if others have an objection?
> 
> Sure, I'll have a look at this today.

That's nice. Thank you.

Regards,
Wanlong Gao

> 
> Regards,
> Jan
> 


------------------------------------------------------------------------------
Everyone hates slow websites. So do we.
Make your web apps faster with AppDynamics
Download AppDynamics Lite for free today:
http://p.sf.net/sfu/appdyn_sfd2d_oct
_______________________________________________
Ltp-list mailing list
Ltp-list@lists.sourceforge.net
https://lists.sourceforge.net/lists/listinfo/ltp-list

^ permalink raw reply	[flat|nested] 12+ messages in thread

end of thread, other threads:[~2012-10-26  8:03 UTC | newest]

Thread overview: 12+ messages (download: mbox.gz / follow: Atom feed)
-- links below jump to the message on this page --
2012-10-23  9:24 [LTP] Regarding shmat01 syscall test Om Prakash PAL
2012-10-23  9:37 ` Wanlong Gao
2012-10-23 10:05   ` Om Prakash PAL
2012-10-24  0:45     ` Wanlong Gao
2012-10-24  6:43       ` Jan Stancek
2012-10-24  7:03         ` Wanlong Gao
2012-10-24  7:49           ` Jan Stancek
2012-10-24  7:51             ` Wanlong Gao
2012-10-24  8:20               ` Jan Stancek
2012-10-26  1:45                 ` Wanlong Gao
2012-10-26  8:01                   ` Jan Stancek
2012-10-26  8:03                     ` Wanlong Gao

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