By: David Kanter (dkanter.delete@this.realworldtech.com), October 1, 2015 12:52 pm
Room: Moderated Discussions
Patrick Chase (patrickjchase.delete@this.gmail.com) on September 30, 2015 10:44 pm wrote:
> SHK (no.delete@this.mail.com) on September 29, 2015 6:38 am wrote:
> > * page split load penalities from 100 cycles to 5 (that's an improvement!)
>
> This appears to be a side-effect of having a second HW page-table walker - In a page-split-load
> scenario the core should now handle both walks in // instead of sequentially.
>
> The true benefits are much broader than that (relatively uncommon) case, though.
I read this as: a page crossing load which hits in the TLB for both pages now takes 5 cycles instead of 100. That is, I don't think the page table walker is involved.
Obviously, if you have a TLB miss - nothing will take anywhere close to 5 cycles.
David
> SHK (no.delete@this.mail.com) on September 29, 2015 6:38 am wrote:
> > * page split load penalities from 100 cycles to 5 (that's an improvement!)
>
> This appears to be a side-effect of having a second HW page-table walker - In a page-split-load
> scenario the core should now handle both walks in // instead of sequentially.
>
> The true benefits are much broader than that (relatively uncommon) case, though.
I read this as: a page crossing load which hits in the TLB for both pages now takes 5 cycles instead of 100. That is, I don't think the page table walker is involved.
Obviously, if you have a TLB miss - nothing will take anywhere close to 5 cycles.
David