<html><head></head><body><div style="font-family:courier new, courier, monaco, monospace, sans-serif;font-size:13px;"><div></div>
<div>Dear Julien,</div><div><br></div><div>Thanks for your response. Is the mentioned task easier in Java or C program?</div><div>indeed, I think it can be easier in Java program. If it is true, I can switch to Java language.</div><div><br></div>
<div id="yahoo_quoted_2976374586" class="yahoo_quoted">
<div style="font-family:'Helvetica Neue', Helvetica, Arial, sans-serif;font-size:13px;color:#26282a;">
<div>
On Thursday, November 30, 2017, 7:15:21 PM GMT+3:30, Julien Desfossez <jdesfossez@efficios.com> wrote:
</div>
<div><br></div>
<div><br></div>
<div><div dir="ltr">On 2017-11-30 10:13 AM, MMM via lttng-dev wrote:<div class="yqt7884770834" id="yqtfd21507"><br clear="none">> Dear Users,<br clear="none">> <br clear="none">> I have posted a couple of email about my problem in the past, while<br clear="none">> nobody response those. It may be true that my question is amateurish,<br clear="none">> but due to the fact that I am a beginner, I can not find the sufficient<br clear="none">> document for solving my problem. I am going to trace a C program that<br clear="none">> read from a file and show the ratio of reads from page cache vs reads<br clear="none">> from disk. I read document of LTTng website, but I can not find<br clear="none">> appropriate explanation for this task. I just need a simple guidance to<br clear="none">> show me the right way for doing it. Could you please help me.<br clear="none">> <br clear="none">> Regards,<br clear="none">> Mehdi.</div><br clear="none"><br clear="none">Hi,<br clear="none"><br clear="none">This is a really non-trivial task to do. Basically, you need to<br clear="none">distinguish the read() syscalls that lead to FS/disk access with the<br clear="none">ones that don't (for the same FD).<br clear="none">The main difficulty is to make the link between the syscall and the<br clear="none">lower-level events and I am not sure we have all the data needed to<br clear="none">establish this link from the payload of the events we have (something<br clear="none">like FD -> FS inode -> block).<br clear="none"><br clear="none">I added Houssem to this thread because I think I remember he did some<br clear="none">work around that, he may have more information.<br clear="none"><br clear="none">Julien</div></div>
</div>
</div></div></body></html>