On 7/23/07, Nick Piggin <[EMAIL PROTECTED]> wrote:
Not talking about swap prefetch itself, but everytime I have asked anyone to instrument or produce some workload where swap prefetch helps, they never do.
[...]
so for all the people who a whining about merging this and don't want to actually work on the code -- post some numbers for where it helps you!!
<Raised eyebrow> You sound frustrated. Perhaps we could be communicating better. I'll start. Unlike others on the cc: line, I don't get paid to hack on the kernel, not even indirectly. So if you find that my lack of providing numbers is giving you heartache, I can only apologize and point at my paying work that requires my attention. That said, I'm willing to run my day to day life through both a swap prefetch kernel and a normal one. *However*, before I go through all the work of instrumenting the damn thing, I'd really like Andrew (or Linus) to lay out his acceptance criteria on the feature. Exactly what *should* I be paying attention to? I've suggested keeping track of process swapin delay total time, and comparing with and without. Is that reasonable? Is it incomplete? Without Andrew's criteria, we're back to where we've been for a long time: lots of work, no forward motion. Perhaps it's a character flaw of mine, but I'd really like to know what would constitute proof here before I invest the effort. Especially given that Con has already written a test case that shows that swap prefetch works, and that I've given you a clear argument for why better (or even perfect) page reclaim can't provide full coverage to all the situations that swap prefetch helps. (Also, it's not like I've got tons free time, y'know? Just like all the rest of you all, I have to pick and choose my battles if I'm going to be effective.) Since this merge period has appeared particularly frazzling for Andrew, I've been keeping silent and waiting for him to get to a point where there's a breather. I didn't feel it would be polite to request yet more work out of him while he had a mess on his hands. But, given this has come to a head, I'm asking now. Andrew? You've always given the impression that you want this run more as an engineering effort than an artistic endeavour, so help us out here. What are your concerns with swap prefetch? What sort of comparative data would you like to see to justify its inclusion, or to prove that it's not needed? Or are we reading too much into the fact that it isn't merged? In short, communicate please, it will help. - To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to [EMAIL PROTECTED] More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
