On 10/26/2012 04:01 PM, Jan Stancek wrote: > > > ----- Original Message ----- >> From: "Wanlong Gao" <[email protected]> >> To: "Jan Stancek" <[email protected]> >> Cc: [email protected], "Om Prakash PAL" >> <[email protected]> >> 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" <[email protected]> >>>> To: "Jan Stancek" <[email protected]> >>>> Cc: [email protected], "Om Prakash PAL" >>>> <[email protected]> >>>> 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" <[email protected]> >>>>>> To: "Jan Stancek" <[email protected]> >>>>>> Cc: [email protected], "Om Prakash PAL" >>>>>> <[email protected]> >>>>>> 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" <[email protected]> >>>>>>>> To: "Om Prakash PAL" <[email protected]> >>>>>>>> Cc: [email protected] >>>>>>>> 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:[email protected]] >>>>>>>>> Sent: Tuesday, October 23, 2012 3:07 PM >>>>>>>>> To: Om Prakash PAL >>>>>>>>> Cc: [email protected] >>>>>>>>> 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 [email protected] https://lists.sourceforge.net/lists/listinfo/ltp-list
