<html>
<head>
<meta content="text/html; charset=windows-1252"
http-equiv="Content-Type">
</head>
<body bgcolor="#FFFFFF" text="#000000">
Sorry for the delay in response.<br>
<br>
<div class="moz-cite-prefix">On 01/15/2016 02:34 PM,
<a class="moz-txt-link-abbreviated" href="mailto:li.ping288@zte.com.cn">li.ping288@zte.com.cn</a> wrote:<br>
</div>
<blockquote
cite="mid:OF22199DEA.2B0E8E7B-ON48257F3B.00318BBE-48257F3B.0031E076@zte.com.cn"
type="cite"><font face="sans-serif" size="2">GLUSTERFS_WRITE_IS_APPEND
Setting in afr_writev
function at glusterfs client end makes the posix_writev in the
server end
deal IO write fops from parallel to serial in consequence.</font>
<br>
<br>
<font face="sans-serif" size="2">i.e. multiple io-worker threads
carrying out IO write fops are blocked in posix_writev to
execute final
write fop pwrite/pwritev in __posix_writev function ONE AFTER
ANOTHER.
</font>
<br>
<br>
<font face="sans-serif" size="2">For example:</font>
<br>
<br>
<font face="sans-serif" size="2">thread1: iot_worker -> ...
->
posix_writev() |</font>
<br>
<font face="sans-serif" size="2">thread2: iot_worker -> ...
->
posix_writev() |</font>
<br>
<font face="sans-serif" size="2">thread3: iot_worker -> ...
->
posix_writev() -> __posix_writev() </font>
<br>
<font face="sans-serif" size="2">thread4: iot_worker -> ...
->
posix_writev() |</font>
<br>
<br>
<font face="sans-serif" size="2">there are 4 iot_worker thread
doing
the 128KB IO write fops as above, but only one can execute
__posix_writev
function and the others have to wait.</font>
<br>
<br>
<font face="sans-serif" size="2">however, if the afr volume is
configured
on with storage.linux-aio which is off in default, the
iot_worker
will use posix_aio_writev instead of posix_writev to write data.</font>
<br>
<font face="sans-serif" size="2">the posix_aio_writev function
won't
be affected by GLUSTERFS_WRITE_IS_APPEND, and the AFR volume
write performance
goes up.</font>
<br>
</blockquote>
I think this is a bug :-(.<br>
<blockquote
cite="mid:OF22199DEA.2B0E8E7B-ON48257F3B.00318BBE-48257F3B.0031E076@zte.com.cn"
type="cite">
<br>
<font face="sans-serif" size="2">So, my question is whether AFR
volume could work fine with storage.linux-aio configuration
which bypass
the GLUSTERFS_WRITE_IS_APPEND setting in afr_writev, </font>
<br>
<font face="sans-serif" size="2">and why glusterfs keeps
posix_aio_writev
different from posix_writev ?</font>
<br>
<br>
<font face="sans-serif" size="2">Any replies to clear my confusion
would
be grateful, and thanks in advance.<br>
</font></blockquote>
<font size="2">What is the workload you have? multiple </font>writers
on same file workloads?<br>
<br>
Pranith<br>
<blockquote
cite="mid:OF22199DEA.2B0E8E7B-ON48257F3B.00318BBE-48257F3B.0031E076@zte.com.cn"
type="cite"><font face="sans-serif" size="2">
</font>
<br>
<pre><font color="blue">
--------------------------------------------------------
ZTE Information Security Notice: The information contained in this mail (and any attachment transmitted herewith) is privileged and confidential and is intended for the exclusive use of the addressee(s). If you are not an intended recipient, any disclosure, reproduction, distribution or other dissemination or use of the information contained is strictly prohibited. If you have received this mail in error, please delete it and notify us immediately.
</font></pre>
<br>
<br>
<fieldset class="mimeAttachmentHeader"></fieldset>
<br>
<pre wrap="">_______________________________________________
Gluster-devel mailing list
<a class="moz-txt-link-abbreviated" href="mailto:Gluster-devel@gluster.org">Gluster-devel@gluster.org</a>
<a class="moz-txt-link-freetext" href="http://www.gluster.org/mailman/listinfo/gluster-devel">http://www.gluster.org/mailman/listinfo/gluster-devel</a></pre>
</blockquote>
<br>
</body>
</html>