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<base href="https://bugs.freedesktop.org/" />
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<th>Bug ID</th>
<td><a class="bz_bug_link
bz_status_NEW "
title="NEW - glBufferSubData doesn't update the buffer"
href="https://bugs.freedesktop.org/show_bug.cgi?id=90734">90734</a>
</td>
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<th>Summary</th>
<td>glBufferSubData doesn't update the buffer
</td>
</tr>
<tr>
<th>Product</th>
<td>Mesa
</td>
</tr>
<tr>
<th>Version</th>
<td>git
</td>
</tr>
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<th>Hardware</th>
<td>x86-64 (AMD64)
</td>
</tr>
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<th>OS</th>
<td>Linux (All)
</td>
</tr>
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<th>Status</th>
<td>NEW
</td>
</tr>
<tr>
<th>Severity</th>
<td>normal
</td>
</tr>
<tr>
<th>Priority</th>
<td>medium
</td>
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<th>Component</th>
<td>Drivers/DRI/i965
</td>
</tr>
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<th>Assignee</th>
<td>idr@freedesktop.org
</td>
</tr>
<tr>
<th>Reporter</th>
<td>kaillasse91@hotmail.fr
</td>
</tr>
<tr>
<th>QA Contact</th>
<td>intel-3d-bugs@lists.freedesktop.org
</td>
</tr></table>
<p>
<div>
<pre>The behaviour of my application is very different with mesa and a Sandy bridge
HD2000 gpu.
Using INTEL_DEBUG=perf I see a lot of
'Using a blit copy to avoid stalling on glBufferSubData(6336, 6408) (0kb) to a
busy (0-72000) buffer object.'
with whatever the range I was updating is.
Getting the buffer back with glGetBufferSubData shows that the buffer is
sometimes not/impartially (?) updated.
Updating the whole buffer or forcing a sync with glFinish corrects the errors.
For info. :
void ShapeCollectionGl::updateBufferRange(int startIdx, int endIdx)
{
glBindVertexArray(vao_);
glBindBuffer(GL_ARRAY_BUFFER, vbo_);
int offPos = shapesGl_[startIdx].offPos;
int sizeData = shapesGl_[endIdx].offPos + shapesGl_[endIdx].pos.size() -
offPos;
// glFinish() here solves the problem
glBufferSubData(GL_ARRAY_BUFFER,
offPos * sizeof(VertexData),
sizeData * sizeof(VertexData),
&bufData_[offPos]);
// reading the buffer back here with glGetBufferSubData shows the
difference
glBindBuffer(GL_ELEMENT_ARRAY_BUFFER, ebo_);
int offIdx = shapesGl_[startIdx].offIdx;
int sizeIdx = shapesGl_[endIdx].offIdx + shapesGl_[endIdx].idx.size() -
offIdx;
glBufferSubData(GL_ELEMENT_ARRAY_BUFFER,
offIdx * sizeof(GLuint),
sizeIdx * sizeof(GLuint),
&bufIdx_[offIdx]);
glBindVertexArray(0);
}
00:02.0 VGA compatible controller [0300]: Intel Corporation 2nd Generation Core
Processor Family Integrated Graphics Controller [8086:0102] (rev 09) (prog-if
00 [VGA controller])
OpenGL core profile version string: 3.3 (Core Profile) Mesa 10.7.0-devel
(git-10aacf5 2015-05-28 trusty-oibaf-ppa)
Linux 4.0.4-040004-generic #201505171336 SMP Sun May 17 17:37:22 UTC 2015
x86_64 x86_64 x86_64 GNU/Linux</pre>
</div>
</p>
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