[rds-devel] FW: RDS -- how to detect peer is gone ?

[Tang, Changqing]

We strongly ask the ability to run both 32bit and 64bit RDS code on 64bit kernel.

--CQ

-----Original Message-----
From: Andy Grover [mailto:andy.grover at oracle.com]
Sent: Wednesday, March 31, 2010 4:40 PM
To: Tang, Changqing
Cc: RDS Devel
Subject: Re: [rds-devel] FW: RDS -- how to detect peer is gone ?

Tang, Changqing wrote:
> Why not ? even IB verbs support both 32bit and 64bit apps.

We support 32bit apps on a 32bit kernel and 64bit apps on a 64bit
kernel. You are talking about some kind of 32bit userspace on a 64bit
kernel. Nobody does that.

-- Andy

>
> --CQ
>
> -----Original Message-----
> From: Andy Grover [mailto:andy.grover at oracle.com]
> Sent: Wednesday, March 31, 2010 1:33 PM
> To: Tang, Changqing
> Cc: RDS Devel
> Subject: Re: [rds-devel] FW: RDS -- how to detect peer is gone ?
>
> Tang, Changqing wrote:
>> Andy, Thank you for your confirmation, when do you have a fix for
>> this 32bit RDS problem on x86_64 system ?
>>
>> --CQ
>
> Running 32 bit apps on 64bit kernel is not supported.
>
> -- Andy
>
>> -----Original Message-----
>> From: Andy Grover [mailto:andy.grover at oracle.com]
>> Sent: Tuesday, March 30, 2010 8:00 PM
>> To: Tang, Changqing
>> Cc: RDS Devel
>> Subject: Re: [rds-devel] FW: RDS -- how to detect peer is gone ?
>>
>> Tang, Changqing wrote:
>>> Andy, I looked 'man cmsg', 'struct rds_get_mr_args' is always 32
>>> bytes.  Here is my test code:
>>>
>>> #include <stdio.h> #include <stdlib.h> #include <sys/socket.h>
>>>
>>> int main ()
>>>
>>> { struct cmsghdr *cmsg; char    cmsgbuf[CMSG_SPACE(32)];  /* using
>>> struct rds_get_mr_args size */
>>>
>>> cmsg = (struct cmsghdr *)cmsgbuf;
>>>
>>> cmsg->cmsg_len = CMSG_SPACE(32); cmsg->cmsg_type = 0;
>>> cmsg->cmsg_level = 1;
>>>
>>> fprintf(stderr, "offset %d\n", (char*)CMSG_DATA(cmsg)-(char*)cmsg); }
>>>
>>>
>>> The offset for 64bit is 16 and for 32bit is 12.
>>>
>>> So if my code is 32bit, I put 'struct rds_get_mr_args' on 12 bytes
>>> offset, but RDS kernel code will get it from 16 bytes offset.
>>>
>>> Am I wrong ?  Thank you again.
>> Hi CQ,
>>
>> First, please always CC rds-devel so this discussion may be archived,
>> and maybe help someone else in the future.
>>
>> Regarding your question -- I think you're correct that 32bit userland
>> will not work with 64bit kernel.
>>
>> Regards -- Andy
>>
>>> --CQ
>>>
>>>
>>>
>>> -----Original Message----- From: Andy Grover
>>> [mailto:andy.grover at oracle.com] Sent: Tuesday, March 30, 2010 1:41 PM
>>>  To: Tang, Changqing; RDS Devel Subject: Re: [rds-devel] FW: RDS --
>>> how to detect peer is gone ?
>>>
>>> Tang, Changqing wrote:
>>>> Andy, One simple question, does 32bit rds-rdma code work on x86_64
>>>> machine ? I noticed that the size of 'struct cmsghdr' is different
>>>> between 32bit and 64bit, If the kernel code is always 64bit, how
>>>> does the RDS kernel code figure out The control message buffer is
>>>> passed as 32bit format?
>>>>
>>>> Do I miss something here ?
>>> See "man cmsg", it describes the various macros that resolve 32/64
>>> differences.
>>>
>>> Regards -- Andy
>>>
>>>> Thank you. --CQ
>>>>
>>>> -----Original Message----- From: Andy Grover
>>>> [mailto:andy.grover at oracle.com] Sent: Tuesday, March 16, 2010 5:44
>>>> PM To: Tang, Changqing Cc: rds-devel at oss.oracle.com Subject: Re:
>>>> [rds-devel] FW: RDS -- how to detect peer is gone ?
>>>>
>>>> Tang, Changqing wrote:
>>>>>> [CQ] yes, the node is up and the process may corrupted. If you
>>>>>> can extend the rds ping message a little bit to process as
>>>>>> optional, that would be wonderful.
>>>>> I don't see why rds's ping functionality as-is is insufficient
>>>>> for what you want to do.
>>>>>
>>>>> [CQ] What do you mean ? how can I use rds ping function as-is to
>>>>> identify process down ?
>>>> Like I said, if the process doesn't respond but the rds ping does,
>>>> then you know the machine is alive but the process is not.
>>>>
>>>> -- Andy
>