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List:       kde-frameworks-devel
Subject:    Re: Review Request 130084: Add a pair of flags forcing fsync during copy loop
From:       David Faure <faure () kde ! org>
Date:       2017-05-05 10:17:55
Message-ID: 20170505101755.2829.45289 () mimi ! kde ! org
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https://git.reviewboard.kde.org/r/130084/#review103187
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src/ioslaves/file/file_unix.cpp (line 89)
<https://git.reviewboard.kde.org/r/130084/#comment68668>

    remove newline after "bool" and before function name
     (Qt/KF5 coding style)



src/ioslaves/file/file_unix.cpp (line 103)
<https://git.reviewboard.kde.org/r/130084/#comment68666>

    &= doesn't do what you think, it's a bit-flag operation and not a boolean \
operation.  
    1=true
    2=true
    1&2=false
    
    You need to use = hasMajorMinor &&, for lack of a &&= in the standard.



src/ioslaves/file/file_unix.cpp (line 109)
<https://git.reviewboard.kde.org/r/130084/#comment68667>

    const auto...
    
    so that first() below doesn't detach.



src/ioslaves/file/file_unix.cpp (line 229)
<https://git.reviewboard.kde.org/r/130084/#comment68669>

    const bool .. to make it clear it's not modified further down


- David Faure


On April 17, 2017, 11:27 a.m., KJ Tsanaktsidis wrote:
> 
> -----------------------------------------------------------
> This is an automatically generated e-mail. To reply, visit:
> https://git.reviewboard.kde.org/r/130084/
> -----------------------------------------------------------
> 
> (Updated April 17, 2017, 11:27 a.m.)
> 
> 
> Review request for KDE Frameworks, Oswald Buddenhagen and Thiago Macieira.
> 
> 
> Repository: kio
> 
> 
> Description
> -------
> 
> When copying a large-ish file (~1-2GB) from very fast storage to very slow storage \
> (e.g. an NVME SSD to a cheap USB flash drive) on a machine with lots of RAM, \
> Dolphin displays a progress bar which finishes in a fraction of a second (i.e. as \
> fast as it takes to read the source file into the Linux page cache). Unmounting the \
> drive then of course takes a long time, with only an indeterminate spinner. 
> This patch adds an option to force fsync during copy jobs, so that the copy \
> progress bar measures how long it will take to actually copy the file to the \
> destination. 
> I've added two flags - Fsync and FsyncCrossFilesystem - to the JobEnum flag. The \
> former will cause all copy operations to fsync during the copy loop, whilst the \
> latter will only fsync copies that are across different filesystems. 
> If this patch gets OK'd, I have another patch which adds support for this into the \
> appropriate places in Dolphin. I would think that at least FsyncCrossFilesystem \
> should be the default, but Fsync always might be a little heavy handed. At the \
> least fsync'ing cross-filesystem copies ensures that the unmount won't take \
> forever. 
> 
> Diffs
> -----
> 
> src/ioslaves/file/CMakeLists.txt b9132ced9d4a08b2cf9f9bbbaa3bd43f026c6469 
> src/ioslaves/file/ConfigureChecks.cmake 5a83d1b9fbe90c851c774e3b467468d93b5a2bd4 
> src/ioslaves/file/config-kioslave-file.h.cmake \
> 372f79d01ad4597aae0b2ae62627648fe7680b64  src/ioslaves/file/file_unix.cpp \
> 3c1b9927e3dd2d0134f77caec6e6b24a0356d26f  
> Diff: https://git.reviewboard.kde.org/r/130084/diff/
> 
> 
> Testing
> -------
> 
> Tested the patch with KDE/Dolphin on Arch Linux, which is version 5.32.0. The diff \
> applies cleanly to master so I assume there shouldn't be any issues there, but I've \
> not actually checked that. As advertised, copying a file to USB flash storage now \
> displays an accurate progress bar. 
> I experimented with how often fsync should be called on my hardware, and I found \
> calling it every ~1M copied caused no decrease in copy performance whilst still \
> providing accurate progress info. That is the setting I've gone with in this patch. \
> I'm open to suggestions on how this could be tuned better though. 
> 
> Thanks,
> 
> KJ Tsanaktsidis
> 
> 


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      This is an automatically generated e-mail. To reply, visit:
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font-size: 9pt; padding: 4px 8px; text-align: left;">  <a \
href="https://git.reviewboard.kde.org/r/130084/diff/2/?file=494464#file494464line89" \
style="color: black; font-weight: bold; text-decoration: \
underline;">src/ioslaves/file/file_unix.cpp</a>  <span style="font-weight: normal;">

     (Diff revision 2)

    </span>
   </th>
  </tr>
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    <th bgcolor="#b1ebb0" style="border-right: 1px solid #C0C0C0;" \
align="right"><font size="2"></font></th>  <td bgcolor="#c5ffc4" width="50%"><pre \
style="font-size: 8pt; line-height: 140%; margin: 0; "></pre></td>  <th \
bgcolor="#b1ebb0" style="border-left: 1px solid #C0C0C0; border-right: 1px solid \
#C0C0C0;" align="right"><font size="2">89</font></th>  <td bgcolor="#c5ffc4" \
width="50%"><pre style="font-size: 8pt; line-height: 140%; margin: 0; "><span \
class="nf">file_is_on_removable_media</span><span class="p">(</span><span \
class="kt">int</span> <span class="n">fd</span><span class="p">)</span></pre></td>  \
</tr>

 </tbody>

</table>

 <div style="margin-left: 2em;">

  <pre style="white-space: pre-wrap; white-space: -moz-pre-wrap; white-space: \
-pre-wrap; white-space: -o-pre-wrap; word-wrap: break-word;"><p style="padding: \
0;text-rendering: inherit;margin: 0;line-height: inherit;white-space: \
inherit;">remove newline after "bool" and before function name  (Qt/KF5 coding \
style)</p></pre>  </div>
</div>
<br />

<div>



<table width="100%" border="0" bgcolor="white" style="border: 1px solid #C0C0C0; \
border-collapse: collapse; margin: 2px padding: 2px;">  <thead>
  <tr>
   <th colspan="4" bgcolor="#F0F0F0" style="border-bottom: 1px solid #C0C0C0; \
font-size: 9pt; padding: 4px 8px; text-align: left;">  <a \
href="https://git.reviewboard.kde.org/r/130084/diff/2/?file=494464#file494464line103" \
style="color: black; font-weight: bold; text-decoration: \
underline;">src/ioslaves/file/file_unix.cpp</a>  <span style="font-weight: normal;">

     (Diff revision 2)

    </span>
   </th>
  </tr>
 </thead>



 
 

 <tbody>

  <tr>
    <th bgcolor="#b1ebb0" style="border-right: 1px solid #C0C0C0;" \
align="right"><font size="2"></font></th>  <td bgcolor="#c5ffc4" width="50%"><pre \
style="font-size: 8pt; line-height: 140%; margin: 0; "></pre></td>  <th \
bgcolor="#b1ebb0" style="border-left: 1px solid #C0C0C0; border-right: 1px solid \
#C0C0C0;" align="right"><font size="2">103</font></th>  <td bgcolor="#c5ffc4" \
width="50%"><pre style="font-size: 8pt; line-height: 140%; margin: 0; ">    <span \
class="n">hasMajorMinor</span> <span class="o">&amp;=</span> <span \
class="n">Solid</span><span class="o">::</span><span class="n">Predicate</span><span \
class="p">(</span></pre></td>  </tr>

 </tbody>

</table>

 <div style="margin-left: 2em;">

  <pre style="white-space: pre-wrap; white-space: -moz-pre-wrap; white-space: \
-pre-wrap; white-space: -o-pre-wrap; word-wrap: break-word;"><p style="padding: \
0;text-rendering: inherit;margin: 0;line-height: inherit;white-space: \
inherit;">&amp;= doesn't do what you think, it's a bit-flag operation and not a \
boolean operation.</p> <p style="padding: 0;text-rendering: inherit;margin: \
0;line-height: inherit;white-space: inherit;">1=true 2=true
1&amp;2=false</p>
<p style="padding: 0;text-rendering: inherit;margin: 0;line-height: \
inherit;white-space: inherit;">You need to use = hasMajorMinor &amp;&amp;, for lack \
of a &amp;&amp;= in the standard.</p></pre>  </div>
</div>
<br />

<div>



<table width="100%" border="0" bgcolor="white" style="border: 1px solid #C0C0C0; \
border-collapse: collapse; margin: 2px padding: 2px;">  <thead>
  <tr>
   <th colspan="4" bgcolor="#F0F0F0" style="border-bottom: 1px solid #C0C0C0; \
font-size: 9pt; padding: 4px 8px; text-align: left;">  <a \
href="https://git.reviewboard.kde.org/r/130084/diff/2/?file=494464#file494464line109" \
style="color: black; font-weight: bold; text-decoration: \
underline;">src/ioslaves/file/file_unix.cpp</a>  <span style="font-weight: normal;">

     (Diff revision 2)

    </span>
   </th>
  </tr>
 </thead>



 
 

 <tbody>

  <tr>
    <th bgcolor="#b1ebb0" style="border-right: 1px solid #C0C0C0;" \
align="right"><font size="2"></font></th>  <td bgcolor="#c5ffc4" width="50%"><pre \
style="font-size: 8pt; line-height: 140%; margin: 0; "></pre></td>  <th \
bgcolor="#b1ebb0" style="border-left: 1px solid #C0C0C0; border-right: 1px solid \
#C0C0C0;" align="right"><font size="2">109</font></th>  <td bgcolor="#c5ffc4" \
width="50%"><pre style="font-size: 8pt; line-height: 140%; margin: 0; ">    <span \
class="k">auto</span> <span class="n">blockdev_list</span> <span class="o">=</span> \
<span class="n">Solid</span><span class="o">::</span><span \
class="n">Device</span><span class="o">::</span><span \
class="n">listFromQuery</span><span class="p">(</span><span \
class="n">hasMajorMinor</span><span class="p">);</span></pre></td>  </tr>

 </tbody>

</table>

 <div style="margin-left: 2em;">

  <pre style="white-space: pre-wrap; white-space: -moz-pre-wrap; white-space: \
-pre-wrap; white-space: -o-pre-wrap; word-wrap: break-word;"><p style="padding: \
0;text-rendering: inherit;margin: 0;line-height: inherit;white-space: inherit;">const \
auto...</p> <p style="padding: 0;text-rendering: inherit;margin: 0;line-height: \
inherit;white-space: inherit;">so that first() below doesn't detach.</p></pre>  \
</div> </div>
<br />

<div>



<table width="100%" border="0" bgcolor="white" style="border: 1px solid #C0C0C0; \
border-collapse: collapse; margin: 2px padding: 2px;">  <thead>
  <tr>
   <th colspan="4" bgcolor="#F0F0F0" style="border-bottom: 1px solid #C0C0C0; \
font-size: 9pt; padding: 4px 8px; text-align: left;">  <a \
href="https://git.reviewboard.kde.org/r/130084/diff/2/?file=494464#file494464line229" \
style="color: black; font-weight: bold; text-decoration: \
underline;">src/ioslaves/file/file_unix.cpp</a>  <span style="font-weight: normal;">

     (Diff revision 2)

    </span>
   </th>
  </tr>
 </thead>



 
 

 <tbody>

  <tr>
    <th bgcolor="#b1ebb0" style="border-right: 1px solid #C0C0C0;" \
align="right"><font size="2"></font></th>  <td bgcolor="#c5ffc4" width="50%"><pre \
style="font-size: 8pt; line-height: 140%; margin: 0; "></pre></td>  <th \
bgcolor="#b1ebb0" style="border-left: 1px solid #C0C0C0; border-right: 1px solid \
#C0C0C0;" align="right"><font size="2">229</font></th>  <td bgcolor="#c5ffc4" \
width="50%"><pre style="font-size: 8pt; line-height: 140%; margin: 0; ">    <span \
class="kt">bool</span> <span class="n">should_fsync</span> <span class="o">=</span> \
<span class="n">file_is_on_removable_media</span><span class="p">(</span><span \
class="n">dest_file</span><span class="p">.</span><span class="n">handle</span><span \
class="p">());</span></pre></td>  </tr>

 </tbody>

</table>

 <div style="margin-left: 2em;">

  <pre style="white-space: pre-wrap; white-space: -moz-pre-wrap; white-space: \
-pre-wrap; white-space: -o-pre-wrap; word-wrap: break-word;"><p style="padding: \
0;text-rendering: inherit;margin: 0;line-height: inherit;white-space: inherit;">const \
bool .. to make it clear it's not modified further down</p></pre>  </div>
</div>
<br />



<p>- David Faure</p>


<br />
<p>On April 17th, 2017, 11:27 a.m. UTC, KJ Tsanaktsidis wrote:</p>








<table bgcolor="#fefadf" width="100%" cellspacing="0" cellpadding="12" style="border: \
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  <td>

<div>Review request for KDE Frameworks, Oswald Buddenhagen and Thiago Macieira.</div>
<div>By KJ Tsanaktsidis.</div>


<p style="color: grey;"><i>Updated April 17, 2017, 11:27 a.m.</i></p>









<div style="margin-top: 1.5em;">
 <b style="color: #575012; font-size: 10pt;">Repository: </b>
kio
</div>


<h1 style="color: #575012; font-size: 10pt; margin-top: 1.5em;">Description </h1>
 <table width="100%" bgcolor="#ffffff" cellspacing="0" cellpadding="10" \
style="border: 1px solid #b8b5a0">  <tr>
  <td>
   <pre style="margin: 0; padding: 0; white-space: pre-wrap; white-space: \
-moz-pre-wrap; white-space: -pre-wrap; white-space: -o-pre-wrap; word-wrap: \
break-word;"><p style="padding: 0;text-rendering: inherit;margin: 0;line-height: \
inherit;white-space: inherit;">When copying a large-ish file (~1-2GB) from very fast \
storage to very slow storage (e.g. an NVME SSD to a cheap USB flash drive) on a \
machine with lots of RAM, Dolphin displays a progress bar which finishes in a \
fraction of a second (i.e. as fast as it takes to read the source file into the Linux \
page cache). Unmounting the drive then of course takes a long time, with only an \
indeterminate spinner.</p> <p style="padding: 0;text-rendering: inherit;margin: \
0;line-height: inherit;white-space: inherit;">This patch adds an option to force \
fsync during copy jobs, so that the copy progress bar measures how long it will take \
to actually copy the file to the destination.</p> <p style="padding: \
0;text-rendering: inherit;margin: 0;line-height: inherit;white-space: inherit;">I've \
added two flags - Fsync and FsyncCrossFilesystem - to the JobEnum flag. The former \
will cause all copy operations to fsync during the copy loop, whilst the latter will \
only fsync copies that are across different filesystems.</p> <p style="padding: \
0;text-rendering: inherit;margin: 0;line-height: inherit;white-space: inherit;">If \
this patch gets OK'd, I have another patch which adds support for this into the \
appropriate places in Dolphin. I would think that at least FsyncCrossFilesystem \
should be the default, but Fsync always might be a little heavy handed. At the least \
fsync'ing cross-filesystem copies ensures that the unmount won't take \
forever.</p></pre>  </td>
 </tr>
</table>


<h1 style="color: #575012; font-size: 10pt; margin-top: 1.5em;">Testing </h1>
<table width="100%" bgcolor="#ffffff" cellspacing="0" cellpadding="10" style="border: \
1px solid #b8b5a0">  <tr>
  <td>
   <pre style="margin: 0; padding: 0; white-space: pre-wrap; white-space: \
-moz-pre-wrap; white-space: -pre-wrap; white-space: -o-pre-wrap; word-wrap: \
break-word;"><p style="padding: 0;text-rendering: inherit;margin: 0;line-height: \
inherit;white-space: inherit;">Tested the patch with KDE/Dolphin on Arch Linux, which \
is version 5.32.0. The diff applies cleanly to master so I assume there shouldn't be \
any issues there, but I've not actually checked that. As advertised, copying a file \
to USB flash storage now displays an accurate progress bar.</p> <p style="padding: \
0;text-rendering: inherit;margin: 0;line-height: inherit;white-space: inherit;">I \
experimented with how often fsync should be called on my hardware, and I found \
calling it every ~1M copied caused no decrease in copy performance whilst still \
providing accurate progress info. That is the setting I've gone with in this patch. \
I'm open to suggestions on how this could be tuned better though.</p></pre>  </td>
 </tr>
</table>


<h1 style="color: #575012; font-size: 10pt; margin-top: 1.5em;">Diffs</b> </h1>
<ul style="margin-left: 3em; padding-left: 0;">

 <li>src/ioslaves/file/CMakeLists.txt <span style="color: \
grey">(b9132ced9d4a08b2cf9f9bbbaa3bd43f026c6469)</span></li>

 <li>src/ioslaves/file/ConfigureChecks.cmake <span style="color: \
grey">(5a83d1b9fbe90c851c774e3b467468d93b5a2bd4)</span></li>

 <li>src/ioslaves/file/config-kioslave-file.h.cmake <span style="color: \
grey">(372f79d01ad4597aae0b2ae62627648fe7680b64)</span></li>

 <li>src/ioslaves/file/file_unix.cpp <span style="color: \
grey">(3c1b9927e3dd2d0134f77caec6e6b24a0356d26f)</span></li>

</ul>

<p><a href="https://git.reviewboard.kde.org/r/130084/diff/" style="margin-left: \
3em;">View Diff</a></p>






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