3 ms·

SuperFetch only hits the first 10 meg of a DLL. If any of these are larger than that, you'll still see significant thrashing on pages located further back in th

SuperFetch only hits the first 10 meg of a DLL. If any of these are larger than that, you'll still see significant thrashing on pages located further back in the binaries. I implemented a similar solution for chrome.dll last summer and it had a gigantic effect on cold start times. Glad to see Mozilla prioritizing startup too.

asadotzler 16y ago
Alex, can you link the bug(s) or patch set for your similar changes?
- mihaip 16y ago
  http://crbug.com/45510 http://crbug.com/45510, http://crrev.com/50386 http://crrev.com/50386, http://crrev.com/51486 http://crrev.com/51486, http://crrev.com/51594 http://crrev.com/51594 and http://crrev.com/54934 http://crrev.com/54934 seem to be appropriate links.
- slightlyoff 16y ago
  Mihai covered it. Here's my rundown: http://infrequently.org/2011/01/on-the-care-and-feeding-of-spinning-disks/ http://infrequently.org/2011/01/on-the-care-and-feeding-of-s...
JonnieCache 16y ago
>SuperFetch only hits the first 10 meg of a DLL. If any of these are larger than that, you'll still see significant thrashing on pages located further back in the binaries Yuck. Is there a good engineering reason for this reliance on the physical location of code within a lib file rather than its logical internal structure? I guess its a compromise they made after running some studies. Still seems sickeningly ugly though. Just like the trick the OP was forced to implement to override this behaviour. Yucketty yuck yuck.
- slightlyoff 16y ago
  Define "logical internal structure"? Most code in a library won't be differentiated by use unless you can provide WPO or PGO-based feedback that you trust as representative. As for the next obvious question ("why not just read in the whole thing?"), I think you can probably guess. I'm not sure how yucky this is. The world is analog. MSFT made things go faster without asking developers to change anything they were doing. I wish more OSes showed more of this sort of user-centric, data-driven prioritization of feature development.
  - JonnieCache 16y ago
    I am clearly much less qualified to speak on this subject than you so I defer to you on this one. All I meant by 'yuck' was that in my limited experience with computer science, whenever there is a solution that involves as blunt a compromise as 'cache the first 10 megabytes,' it isn't usually too long before that solution is known as the 'naive' solution.
xpaulbettsx 16y ago
Interesting. I've worked on SuperFetch and I didn't know that!
- slightlyoff 16y ago
  It's likely that my understanding of the situation is at least partially confused. The "SuperFetch" branding covers a lot of systems with some observably complex interactions. From my recollection of the XPerf traces, we saw misses 10+ MB back in the DLLs and just ascribed it to "SuperFetch" on the front half. If you could tell me if that's causal, it'd be awesome = )

asadotzler 16y ago

Alex, can you link the bug(s) or patch set for your similar changes?

mihaip 16y ago
http://crbug.com/45510 http://crbug.com/45510, http://crrev.com/50386 http://crrev.com/50386, http://crrev.com/51486 http://crrev.com/51486, http://crrev.com/51594 http://crrev.com/51594 and http://crrev.com/54934 http://crrev.com/54934 seem to be appropriate links.
slightlyoff 16y ago
Mihai covered it. Here's my rundown: http://infrequently.org/2011/01/on-the-care-and-feeding-of-spinning-disks/ http://infrequently.org/2011/01/on-the-care-and-feeding-of-s...

JonnieCache 16y ago

>SuperFetch only hits the first 10 meg of a DLL. If any of these are larger than that, you'll still see significant thrashing on pages located further back in the binaries Yuck. Is there a good engineering reason for this reliance on the physical location of code within a lib file rather than its logical internal structure? I guess its a compromise they made after running some studies. Still seems sickeningly ugly though. Just like the trick the OP was forced to implement to override this behaviour. Yucketty yuck yuck.

slightlyoff 16y ago
Define "logical internal structure"? Most code in a library won't be differentiated by use unless you can provide WPO or PGO-based feedback that you trust as representative. As for the next obvious question ("why not just read in the whole thing?"), I think you can probably guess. I'm not sure how yucky this is. The world is analog. MSFT made things go faster without asking developers to change anything they were doing. I wish more OSes showed more of this sort of user-centric, data-driven prioritization of feature development.
- JonnieCache 16y ago
  I am clearly much less qualified to speak on this subject than you so I defer to you on this one. All I meant by 'yuck' was that in my limited experience with computer science, whenever there is a solution that involves as blunt a compromise as 'cache the first 10 megabytes,' it isn't usually too long before that solution is known as the 'naive' solution.

xpaulbettsx 16y ago

Interesting. I've worked on SuperFetch and I didn't know that!

slightlyoff 16y ago
It's likely that my understanding of the situation is at least partially confused. The "SuperFetch" branding covers a lot of systems with some observably complex interactions. From my recollection of the XPerf traces, we saw misses 10+ MB back in the DLLs and just ascribed it to "SuperFetch" on the front half. If you could tell me if that's causal, it'd be awesome = )