prefetches

Massive DNS lookup errors due to the feature in 3.5 that prefetches DNS information.

Firefox 3.5 Officially Available For Download | Lifehacker Australia 2009

Link prefetching downloads, or prefetches, links and other documents from a web page that you're viewing and stores the items in the browser's cache.

Daveman's Blog David Fulton 2005

Link prefetching downloads, or prefetches, links and other documents from a web page that you're viewing and stores the items in the browser's cache.

Archive 2005-09-01 David Fulton 2005

It takes a couple of hundred cycles to fetch data from memory, so I end up fetching for eight iterations ahead (eight is the maximum number of outstanding prefetches on that processor).

Sun Bloggers 2009

Of course with this change the prefetches issued will now be dropped if there is a TLB miss, and it is possible that could cause a slowdown for the loads in the loop - which is a trade-off.

Sun Bloggers 2009

L4 has 1 loads, 1 stores, 0 prefetches, 0 FPadds, 1 FPmuls, and 0 FPdivs per iteration

Sun Bloggers 2009

L3 has 0 loads, 1 stores, 0 prefetches, 3 FPadds, 1 FPmuls, and 0 FPdivs per iteration

Sun Bloggers 2009

If the data resides on a new page, and prefetches do not cause TLB misses, then eight iterations will complete before a load or store touches the new page of memory and brings the mapping into the TLB.

Sun Bloggers 2009

However, if the prefetches are strong prefetches, then the first strong prefetch will cause the mapping to be brought into the TLB, and all the prefetches will hit in the TLB.

Sun Bloggers 2009

The eight prefetches that were issued for those iterations will have been dropped and all the iterations will see the full memory latency (a total of 200*8 = 1600 cycles of cost).

Sun Bloggers 2009