<html><head><meta http-equiv="Content-Type" content="text/html charset=windows-1252"></head><body style="word-wrap: break-word; -webkit-nbsp-mode: space; -webkit-line-break: after-white-space; "><div><blockquote type="cite"><div lang="EN-GB" link="#0563C1" vlink="#954F72" style="font-family: Helvetica; font-size: medium; font-style: normal; font-variant: normal; font-weight: normal; letter-spacing: normal; line-height: normal; orphans: 2; text-align: -webkit-auto; text-indent: 0px; text-transform: none; white-space: normal; widows: 2; word-spacing: 0px; -webkit-text-size-adjust: auto; -webkit-text-stroke-width: 0px; "><div class="WordSection1" style="page: WordSection1; "><div style="margin: 0cm 0cm 0.0001pt; font-size: 12pt; font-family: 'Times New Roman', serif; "><span style="font-family: Calibri, sans-serif; "> </span></div><div style="margin: 0cm 0cm 0.0001pt 36pt; font-size: 12pt; font-family: 'Times New Roman', serif; text-indent: -18pt; "><span style="font-family: Symbol; "><span>·<span style="font-style: normal; font-variant: normal; font-weight: normal; font-size: 7pt; line-height: normal; font-family: 'Times New Roman'; "> <span class="Apple-converted-space"> </span></span></span></span><b><span style="font-family: Calibri, sans-serif; ">Everyone</span></b><span style="font-family: Calibri, sans-serif; ">. It’s really hard to keep focus on keeping GHC’s compilation time and space down. Everyone is usually focused on bugs and features. It would be incredibly helpful if someone, or a small group, could build a profiled version of GHC 7.8, 7.10, and HEAD, and track down what is happening. Usually there are multiple causes, but a factor of 7.5 ought not to be hard to nail down.<o:p></o:p></span></div><div style="margin: 0cm 0cm 0.0001pt 36pt; font-size: 12pt; font-family: 'Times New Roman', serif; "><span style="font-family: Calibri, sans-serif; "> </span></div><div style="margin: 0cm 0cm 0.0001pt 36pt; font-size: 12pt; font-family: 'Times New Roman', serif; "><span style="font-family: Calibri, sans-serif; ">Please!<o:p></o:p></span></div></div></div></blockquote><br></div><div>This is a great newcomer-to-ghc-hacking task. It's both relatively easy to do and gives a newcomer a chance to tour the codebase. The person doing the profiling doesn't also have to fix the bug. Just knowing what module or component of GHC is causing the trouble helps immensely.</div><div><br></div><div>As a further plug: when a change I made introduced a performance regression, I went into the debugging process very warily, expecting profiling GHC to be painful. It was just the opposite -- remarkably straightforward and able to produce results without terribly much effort. On the other hand, it does generally require having multiple (profiled) builds of GHC to get meaningful comparisons.</div><div><br></div><div>Thanks to whoever takes this on!</div><div><br></div><div>Richard</div></body></html>