Re: How can I get the maximum shared memory segment size in program?
Re: How can I get the maximum shared memory segment size in program?
- Subject: Re: How can I get the maximum shared memory segment size in program?
- From: bady yu <email@hidden>
- Date: Fri, 4 Jan 2008 17:17:42 +0800
Terry,
You are right.
In my original codes, I declared shmmax variable as long. And
sysctlbyname can't return the correct value.
After I changed shmmax to long long. sysctlbyname return the exact
value as sysctl command.
Then my question is how can I know the exact type of each return value
for kinds of keys? Although I can know some information from "man 8
sysctl", I don't know the exact type of the integer/string/struct,
like whether integer is long long , long or something else.
On Dec 31, 2007, at 4:38 AM, Terry Lambert wrote:
You did not provie the types of len or shmmax, nor whether or not
len contains sizeof(shmmax), nor whether you are calling this from a
32 or 64 bit program. But I suspect you are passing the wrong type
and size in to the sysctlbyname() call.
-- Terry
On Dec 28, 2007, at 9:34 PM, bady yu <email@hidden> wrote:
I can use "sysctl kern.sysv.shmmax" or "ipcs -M" to get the
integer(4194304). But they are both command line tools. It is not
convenient to call it inside the problem.
I also have tried to use the sysctlbyname system call:
sysctlbyname("kern.sysv.shmmax", &shmmax, &len, NULL, NULL).
Although this call return 0, the shmmax variable does not hold the
correct value.
By the way, my system is Leopard.
Can anybody tell me an appropriate way? Thank you in advance!
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