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List:       kde-frameworks-devel
Subject:    Re: Review Request 130084: Add a pair of flags forcing fsync during copy loop
From:       Oswald Buddenhagen <ossi () kde ! org>
Date:       2017-05-05 8:25:13
Message-ID: 20170505082513.2829.71179 () mimi ! kde ! org
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https://git.reviewboard.kde.org/r/130084/#review103186
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src/ioslaves/file/file_unix.cpp (line 112)
<https://git.reviewboard.kde.org/r/130084/#comment68663>

    typo



src/ioslaves/file/file_unix.cpp (line 138)
<https://git.reviewboard.kde.org/r/130084/#comment68664>

    why are you testing hotpluggable? what's the exact definition in this \
context? technically, any sata drive is hotpluggable ...



src/ioslaves/file/file_unix.cpp (line 324)
<https://git.reviewboard.kde.org/r/130084/#comment68665>

    i'd use some parens here to make it more readable.


- Oswald Buddenhagen


On April 17, 2017, 1:27 p.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, 1:27 p.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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href="https://git.reviewboard.kde.org/r/130084/diff/2/?file=494464#file494464line112" \
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>
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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">112</font></th>  <td bgcolor="#c5ffc4" width="50%"><pre \
style="font-size: 8pt; line-height: 140%; margin: 0; ">        <span \
class="c1">// I suppose it could have just been removed (althouth there \
isn&#39;t much</span></pre></td>  </tr>

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 <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;">typo</p></pre>  </div>
</div>
<br />

<div>



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#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#file494464line138" \
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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  <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">138</font></th>  <td bgcolor="#c5ffc4" width="50%"><pre \
style="font-size: 8pt; line-height: 140%; margin: 0; ">    <span \
class="k">return</span> <span class="n">real_storagedrive</span><span \
class="o">-&gt;</span><span class="n">isRemovable</span><span \
class="p">()</span> <span class="o">||</span> <span \
class="n">real_storagedrive</span><span class="o">-&gt;</span><span \
class="n">isHotpluggable</span><span class="p">();</span></pre></td>  </tr>

 </tbody>

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 <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;">why are you testing \
hotpluggable? what's the exact definition in this context? technically, any \
sata drive is hotpluggable ...</p></pre>  </div>
</div>
<br />

<div>



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#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#file494464line324" \
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">324</font></th>  <td bgcolor="#c5ffc4" width="50%"><pre \
style="font-size: 8pt; line-height: 140%; margin: 0; ">        <span \
class="k">if</span> <span class="p">(</span><span \
class="n">should_fsync</span> <span class="o">&amp;&amp;</span> <span \
class="n">niters</span> <span class="o">%</span> <span \
class="mi">128</span> <span class="o">==</span> <span \
class="mi">0</span><span class="p">)</span> <span \
class="p">{</span></pre></td>  </tr>

 </tbody>

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 <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;">i'd use some parens here to \
make it more readable.</p></pre>  </div>
</div>
<br />



<p>- Oswald Buddenhagen</p>


<br />
<p>On April 17th, 2017, 1:27 p.m. CEST, KJ Tsanaktsidis wrote:</p>








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<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, 1:27 p.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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