Re: How to determine whether a file was opened O_DIRECT?

[Eugene Teo <eteo@redhat.com>]

Helge Hafting wrote:
> Böszörményi Zoltán wrote:
>> Hi,
>>
>> I would like to run some diagnostics on a database
>> process and I would like to know what flags it used
>> for opening its files. Is there any way to get this info?
>>
>> Thanks in advance,
>> Zoltán Böszörményi
>>   
> 1. Look at the source code for the database - if you have it.
> 2. Run your database under strace, then search the voluminous
>    output for "open" calls and look at the flags.
> 3. Patch your kernel to "printk" information whenever
>    someone opens with O_DIRECT.

$ stap -x PID -e 'probe syscall.open { if (target() == pid()) log(argstr) }' \
| grep O_DIRECT
"/net", O_RDONLY|O_DIRECTORY|O_LARGEFILE|O_NONBLOCK
"/net", O_RDONLY|O_DIRECTORY|O_LARGEFILE|O_NONBLOCK
...

http://www.sourceware.org/systemtap

Eugene
-- 
eteo redhat.com  ph: +65 6490 4142  http://www.kernel.org/~eugeneteo
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