Hi Manish,
On 07/26/2011 10:22 AM, Manish Katiyar wrote:
> On Mon, Jul 25, 2011 at 9:41 PM, Manish Katiyar<mkatiyar@xxxxxxxxx> wrote:
>> On Mon, Jul 25, 2011 at 9:29 PM, Abhijit Pawar<apawar.linux@xxxxxxxxx> wrote:
>>> Hi Dave,
>>> On 07/25/2011 09:20 PM, Dave Hylands wrote:
>>>> Hi Abhijit,
>>>>
>>>> On Mon, Jul 25, 2011 at 6:35 AM, Abhijit Pawar<apawar.linux@xxxxxxxxx> wrote:
>>>>> On 07/25/2011 05:29 PM, Naveen Kumar wrote:
>>>>>
>>>>> You can use command ulimit -a, there you can check the limit for a process.
>>>>>
>>>>> Thanks,
>>>>> Naveen
>>>>>
>>>>> Ulimit gives 1024 as open file limit. In struct task_struct it has a member
>>>>> called struct files_struct *files;
>>>>>
>>>>> I tried checking for this member and the limit however I am not able to
>>>>> decide correctly why the limit is 1024.
>>>>> Also, is there any distinction between 32 bit and 64 bit systems for this
>>>>> limit?
>>>> My 64-bit system reports 1024 as well.
>>>>
>>>> I have no troubles compiling kernels.
>>>>
>>> Thanks. Yes, on my 64 bit Fedora 15 I get same value as yours.
>>>
>>> What I am interested in is knowing why the limit is on 1024 File
>>> Descriptors? That means 1024 Inodes. AFAIK there isnt anything written
>>> in filesystem code which will put this limit of 1024 inodes for a process.
>>> This means its very specific to the process.
>>> Unfortunately I am know having details on the process front. Is there
>>> anything which you or anyone aware in process area because of which this
>>> limit is there?
>> man getdtablesize
> and if you trace the kernel code, it comes from the limits of the init
> task, which is hard coded during creation. You can get/set these
> values using getrlimit/setrlimit.
>
>
> include/linux/init_task.h
> 33 #define INIT_SIGNALS(sig) { \
> .................
> .................
> 41 .rlim = INIT_RLIMITS,
> ..............
>
> include/asm-generic/resource.h
> 72 #define INIT_RLIMITS \
> 73 { \
> 74 [RLIMIT_CPU] = { RLIM_INFINITY, RLIM_INFINITY }, \
> 75 [RLIMIT_FSIZE] = { RLIM_INFINITY, RLIM_INFINITY }, \
> 76 [RLIMIT_DATA] = { RLIM_INFINITY, RLIM_INFINITY }, \
> 77 [RLIMIT_STACK] = { _STK_LIM, _STK_LIM_MAX }, \
> 78 [RLIMIT_CORE] = { 0, RLIM_INFINITY }, \
> 79 [RLIMIT_RSS] = { RLIM_INFINITY, RLIM_INFINITY }, \
> 80 [RLIMIT_NPROC] = { 0, 0 }, \
> 81 [RLIMIT_NOFILE] = { INR_OPEN_CUR, INR_OPEN_MAX }, \
> ...............
> ..............
>
> include/linux/fs.h
> 25 #undef NR_OPEN
> 26 #define INR_OPEN_CUR 1024 /* Initial setting for nfile rlimits */
> 27 #define INR_OPEN_MAX 4096 /* Hard limit for nfile rlimits */
>
>
> HTH
This is really helpful. Thanks.
Regards,
Abhijit Pawar
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