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<h3 style="margin-top: 20px; margin-bottom: 10px;">
Matthew Pickering pushed to branch wip/testsuite-stack-size at <a href="https://gitlab.haskell.org/ghc/ghc">Glasgow Haskell Compiler / GHC</a>
</h3>
<h4 style="margin-top: 10px; margin-bottom: 10px;">
Commits:
</h4>
<ul>
<li>
<strong style="font-weight: bold;"><a href="https://gitlab.haskell.org/ghc/ghc/-/commit/21163368a188eb8c692329afd744f81ecb5e2a9b">21163368</a></strong>
<div>
<span> by Matthew Pickering </span> <i> at 2023-05-30T09:34:22+01:00 </i>
</div>
<pre class="commit-message" style='white-space: pre-wrap; display: block; font-size: 0.875rem; color: #333238; position: relative; font-family: var(--default-mono-font, "Menlo"),"DejaVu Sans Mono","Liberation Mono","Consolas","Ubuntu Mono","Courier New","andale mono","lucida console",monospace; word-break: break-all; word-wrap: break-word; background-color: #fbfafd; border-radius: 2px; margin: 0; padding: 8px 12px; border: 1px solid #dcdcde;'>testsuite: Pass -kb16k -kc128k for performance tests

Setting a larger stack chunk size gives a greater protection
from stack thrashing (where the repeated overflow/underflow allocates a lot of
stack chunks which sigificantly impact allocations). This
stabilises some tests against differences cause by more things being
pushed onto the stack.

The performance tests are generally testing work done by the compiler,
using allocation as a proxy, so removing/stabilising the allocations due
to the stack gives us more stable tests which are also more sensitive
to actual changes in compiler performance.

The tests which increase are ones where we compile a lot of modules, and
for each module we spawn a thread to compile the module in. Therefore
increasing these numbers has a multiplying effect on these tests because
there are many more stacks which we can increase in size.

The most significant improvements though are cases such as T8095 which
reduce significantly in allocations (30%). This isn't a performance
improvement really but just helps stabilise the test against this
threshold set by the defaults.

Fixes #23439

-------------------------
Metric Decrease:
    InstanceMatching
    T14683
    T8095
    T9872b_defer
    T9872d
    T9961
    hie002
    T19695
    T3064
Metric Increase:
    MultiLayerModules
    T13701
    T14697
-------------------------
</pre>
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1 changed file:
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<li class="file-stats">
<a href="#c591f85f122007bac88228c5ff6fd76b40e6a811">
testsuite/driver/testlib.py
</a>
</li>
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<h4 style="margin-top: 10px; margin-bottom: 10px;">
Changes:
</h4>
<li id="c591f85f122007bac88228c5ff6fd76b40e6a811">
<a href="https://gitlab.haskell.org/ghc/ghc/-/commit/21163368a188eb8c692329afd744f81ecb5e2a9b#c591f85f122007bac88228c5ff6fd76b40e6a811"><strong style="font-weight: bold;">testsuite/driver/testlib.py</strong></a>
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<td class="line_content match" style="color: rgba(31,30,36,0.24); padding: inherit;" bgcolor="#fbfafd">@@ -1791,7 +1791,11 @@ async def simple_build(name: Union[TestName, str],</td>
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<td class="line_content" style="padding: inherit;"><pre style='display: block; font-size: 0.875rem; color: #333238; position: relative; font-family: var(--default-mono-font, "Menlo"),"DejaVu Sans Mono","Liberation Mono","Consolas","Ubuntu Mono","Courier New","andale mono","lucida console",monospace; word-break: break-all; word-wrap: break-word; background-color: inherit; border-radius: 2px; margin: 0; padding: 0; border: inherit solid #dcdcde;'> <span id="LC1791" class="line" lang="python"></span>
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<td class="old_line diff-line-num" data-linenumber="1792" style="width: 35px; color: rgba(31,30,36,0.24); border-right-width: 1px; border-right-color: #ececef; border-right-style: solid; padding: inherit;" align="right" bgcolor="#fbfafd">
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<td class="new_line diff-line-num" data-linenumber="1792" style="width: 35px; color: rgba(31,30,36,0.24); border-right-width: 1px; border-right-color: #ececef; border-right-style: solid; padding: inherit;" align="right" bgcolor="#fbfafd">
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<td class="line_content" style="padding: inherit;"><pre style='display: block; font-size: 0.875rem; color: #333238; position: relative; font-family: var(--default-mono-font, "Menlo"),"DejaVu Sans Mono","Liberation Mono","Consolas","Ubuntu Mono","Courier New","andale mono","lucida console",monospace; word-break: break-all; word-wrap: break-word; background-color: inherit; border-radius: 2px; margin: 0; padding: 0; border: inherit solid #dcdcde;'> <span id="LC1792" class="line" lang="python">    <span class="n" style="color: #333;">stats_file</span> <span class="o" style="font-weight: 600;">=</span> <span class="n" style="color: #333;">name</span> <span class="o" style="font-weight: 600;">+</span> <span class="s" style="color: #d14;">'.comp.stats'</span></span>
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1793
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<td class="new_line diff-line-num" data-linenumber="1793" style="width: 35px; color: rgba(31,30,36,0.24); border-right-width: 1px; border-right-color: #ececef; border-right-style: solid; padding: inherit;" align="right" bgcolor="#fbfafd">
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<td class="line_content" style="padding: inherit;"><pre style='display: block; font-size: 0.875rem; color: #333238; position: relative; font-family: var(--default-mono-font, "Menlo"),"DejaVu Sans Mono","Liberation Mono","Consolas","Ubuntu Mono","Courier New","andale mono","lucida console",monospace; word-break: break-all; word-wrap: break-word; background-color: inherit; border-radius: 2px; margin: 0; padding: 0; border: inherit solid #dcdcde;'> <span id="LC1793" class="line" lang="python">    <span class="k" style="font-weight: 600;">if</span> <span class="n" style="color: #333;">isCompilerStatsTest</span><span class="p">():</span></span>
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<td class="old_line diff-line-num old" data-linenumber="1794" style="width: 35px; color: rgba(31,30,36,0.24); border-right-width: 1px; border-right-color: #fac5cd; border-right-style: solid; padding: inherit;" align="right" bgcolor="#f9d7dc">
1794
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<td class="new_line diff-line-num old" data-linenumber="1794" style="width: 35px; color: rgba(31,30,36,0.24); border-right-width: 1px; border-right-color: #fac5cd; border-right-style: solid; padding: inherit;" align="right" bgcolor="#f9d7dc">
 
</td>
<td class="line_content old" style="padding: inherit;" bgcolor="#fbe9eb"><pre style='display: block; font-size: 0.875rem; color: #333238; position: relative; font-family: var(--default-mono-font, "Menlo"),"DejaVu Sans Mono","Liberation Mono","Consolas","Ubuntu Mono","Courier New","andale mono","lucida console",monospace; word-break: break-all; word-wrap: break-word; background-color: inherit; border-radius: 2px; margin: 0; padding: 0; border: inherit solid #dcdcde;'>-<span id="LC1794" class="line" lang="python">        <span class="n" style="color: #333;">extra_hc_opts</span> <span class="o" style="font-weight: 600;">+=</span> <span class="s" style="color: #d14;">' +RTS -V0 -t'</span> <span class="o" style="font-weight: 600;">+</span> <span class="n" style="color: #333;">stats_file</span> <span class="o" style="font-weight: 600;">+</span> <span class="s" style="color: #d14;">' --machine-readable -RTS'</span></span>
</pre></td>
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<td class="old_line diff-line-num new" data-linenumber="1795" style="width: 35px; color: rgba(31,30,36,0.24); border-right-width: 1px; border-right-color: #c7f0d2; border-right-style: solid; padding: inherit;" align="right" bgcolor="#ddfbe6">
 
</td>
<td class="new_line diff-line-num new" data-linenumber="1794" style="width: 35px; color: rgba(31,30,36,0.24); border-right-width: 1px; border-right-color: #c7f0d2; border-right-style: solid; padding: inherit;" align="right" bgcolor="#ddfbe6">
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<td class="line_content new" style="padding: inherit;" bgcolor="#ecfdf0"><pre style='display: block; font-size: 0.875rem; color: #333238; position: relative; font-family: var(--default-mono-font, "Menlo"),"DejaVu Sans Mono","Liberation Mono","Consolas","Ubuntu Mono","Courier New","andale mono","lucida console",monospace; word-break: break-all; word-wrap: break-word; background-color: inherit; border-radius: 2px; margin: 0; padding: 0; border: inherit solid #dcdcde;'>+<span id="LC1794" class="line" lang="python">        <span class="c1" style="color: #998; font-style: italic;"># Set a bigger chunk size to reduce variation due to additional under/overflowing</span></span>
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<td class="old_line diff-line-num new" data-linenumber="1795" style="width: 35px; color: rgba(31,30,36,0.24); border-right-width: 1px; border-right-color: #c7f0d2; border-right-style: solid; padding: inherit;" align="right" bgcolor="#ddfbe6">
 
</td>
<td class="new_line diff-line-num new" data-linenumber="1795" style="width: 35px; color: rgba(31,30,36,0.24); border-right-width: 1px; border-right-color: #c7f0d2; border-right-style: solid; padding: inherit;" align="right" bgcolor="#ddfbe6">
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<td class="line_content new" style="padding: inherit;" bgcolor="#ecfdf0"><pre style='display: block; font-size: 0.875rem; color: #333238; position: relative; font-family: var(--default-mono-font, "Menlo"),"DejaVu Sans Mono","Liberation Mono","Consolas","Ubuntu Mono","Courier New","andale mono","lucida console",monospace; word-break: break-all; word-wrap: break-word; background-color: inherit; border-radius: 2px; margin: 0; padding: 0; border: inherit solid #dcdcde;'>+<span id="LC1795" class="line" lang="python">        <span class="c1" style="color: #998; font-style: italic;"># The tests are attempting to test how much work the compiler is doing by proxy of</span></span>
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<td class="old_line diff-line-num new" data-linenumber="1795" style="width: 35px; color: rgba(31,30,36,0.24); border-right-width: 1px; border-right-color: #c7f0d2; border-right-style: solid; padding: inherit;" align="right" bgcolor="#ddfbe6">
 
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<td class="new_line diff-line-num new" data-linenumber="1796" style="width: 35px; color: rgba(31,30,36,0.24); border-right-width: 1px; border-right-color: #c7f0d2; border-right-style: solid; padding: inherit;" align="right" bgcolor="#ddfbe6">
1796
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<td class="line_content new" style="padding: inherit;" bgcolor="#ecfdf0"><pre style='display: block; font-size: 0.875rem; color: #333238; position: relative; font-family: var(--default-mono-font, "Menlo"),"DejaVu Sans Mono","Liberation Mono","Consolas","Ubuntu Mono","Courier New","andale mono","lucida console",monospace; word-break: break-all; word-wrap: break-word; background-color: inherit; border-radius: 2px; margin: 0; padding: 0; border: inherit solid #dcdcde;'>+<span id="LC1796" class="line" lang="python">        <span class="c1" style="color: #998; font-style: italic;"># bytes allocated. The additional allocations caused by stack overflow can cause</span></span>
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<td class="new_line diff-line-num new" data-linenumber="1797" style="width: 35px; color: rgba(31,30,36,0.24); border-right-width: 1px; border-right-color: #c7f0d2; border-right-style: solid; padding: inherit;" align="right" bgcolor="#ddfbe6">
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<td class="line_content new" style="padding: inherit;" bgcolor="#ecfdf0"><pre style='display: block; font-size: 0.875rem; color: #333238; position: relative; font-family: var(--default-mono-font, "Menlo"),"DejaVu Sans Mono","Liberation Mono","Consolas","Ubuntu Mono","Courier New","andale mono","lucida console",monospace; word-break: break-all; word-wrap: break-word; background-color: inherit; border-radius: 2px; margin: 0; padding: 0; border: inherit solid #dcdcde;'>+<span id="LC1797" class="line" lang="python">        <span class="c1" style="color: #998; font-style: italic;"># spurious failures if you trip over the limit (see #23439)</span></span>
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<td class="old_line diff-line-num new" data-linenumber="1795" style="width: 35px; color: rgba(31,30,36,0.24); border-right-width: 1px; border-right-color: #c7f0d2; border-right-style: solid; padding: inherit;" align="right" bgcolor="#ddfbe6">
 
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<td class="new_line diff-line-num new" data-linenumber="1798" style="width: 35px; color: rgba(31,30,36,0.24); border-right-width: 1px; border-right-color: #c7f0d2; border-right-style: solid; padding: inherit;" align="right" bgcolor="#ddfbe6">
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<td class="line_content new" style="padding: inherit;" bgcolor="#ecfdf0"><pre style='display: block; font-size: 0.875rem; color: #333238; position: relative; font-family: var(--default-mono-font, "Menlo"),"DejaVu Sans Mono","Liberation Mono","Consolas","Ubuntu Mono","Courier New","andale mono","lucida console",monospace; word-break: break-all; word-wrap: break-word; background-color: inherit; border-radius: 2px; margin: 0; padding: 0; border: inherit solid #dcdcde;'>+<span id="LC1798" class="line" lang="python">        <span class="n" style="color: #333;">extra_hc_opts</span> <span class="o" style="font-weight: 600;">+=</span> <span class="s" style="color: #d14;">' +RTS -kc128k -kb16k -V0 -t'</span> <span class="o" style="font-weight: 600;">+</span> <span class="n" style="color: #333;">stats_file</span> <span class="o" style="font-weight: 600;">+</span> <span class="s" style="color: #d14;">' --machine-readable -RTS'</span></span>
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<td class="line_content" style="padding: inherit;"><pre style='display: block; font-size: 0.875rem; color: #333238; position: relative; font-family: var(--default-mono-font, "Menlo"),"DejaVu Sans Mono","Liberation Mono","Consolas","Ubuntu Mono","Courier New","andale mono","lucida console",monospace; word-break: break-all; word-wrap: break-word; background-color: inherit; border-radius: 2px; margin: 0; padding: 0; border: inherit solid #dcdcde;'> <span id="LC1799" class="line" lang="python">    <span class="k" style="font-weight: 600;">if</span> <span class="n" style="color: #333;">backpack</span><span class="p">:</span></span>
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1796
</td>
<td class="new_line diff-line-num" data-linenumber="1800" style="width: 35px; color: rgba(31,30,36,0.24); border-right-width: 1px; border-right-color: #ececef; border-right-style: solid; padding: inherit;" align="right" bgcolor="#fbfafd">
1800
</td>
<td class="line_content" style="padding: inherit;"><pre style='display: block; font-size: 0.875rem; color: #333238; position: relative; font-family: var(--default-mono-font, "Menlo"),"DejaVu Sans Mono","Liberation Mono","Consolas","Ubuntu Mono","Courier New","andale mono","lucida console",monospace; word-break: break-all; word-wrap: break-word; background-color: inherit; border-radius: 2px; margin: 0; padding: 0; border: inherit solid #dcdcde;'> <span id="LC1800" class="line" lang="python">        <span class="n" style="color: #333;">extra_hc_opts</span> <span class="o" style="font-weight: 600;">+=</span> <span class="s" style="color: #d14;">' -outputdir '</span> <span class="o" style="font-weight: 600;">+</span> <span class="n" style="color: #333;">name</span> <span class="o" style="font-weight: 600;">+</span> <span class="s" style="color: #d14;">'.out'</span></span>
</pre></td>
</tr>
<tr class="line_holder" style="line-height: 1.6;">
<td class="old_line diff-line-num" data-linenumber="1797" style="width: 35px; color: rgba(31,30,36,0.24); border-right-width: 1px; border-right-color: #ececef; border-right-style: solid; padding: inherit;" align="right" bgcolor="#fbfafd">
1797
</td>
<td class="new_line diff-line-num" data-linenumber="1801" style="width: 35px; color: rgba(31,30,36,0.24); border-right-width: 1px; border-right-color: #ececef; border-right-style: solid; padding: inherit;" align="right" bgcolor="#fbfafd">
1801
</td>
<td class="line_content" style="padding: inherit;"><pre style='display: block; font-size: 0.875rem; color: #333238; position: relative; font-family: var(--default-mono-font, "Menlo"),"DejaVu Sans Mono","Liberation Mono","Consolas","Ubuntu Mono","Courier New","andale mono","lucida console",monospace; word-break: break-all; word-wrap: break-word; background-color: inherit; border-radius: 2px; margin: 0; padding: 0; border: inherit solid #dcdcde;'> <span id="LC1801" class="line" lang="python"></span>
</pre></td>
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