Messages in this thread | | | Date | Fri, 27 Apr 2007 22:25:44 +1000 | From | Nick Piggin <> | Subject | Re: [00/17] Large Blocksize Support V3 |
| |
Christoph Lameter wrote: > On Fri, 27 Apr 2007, Nick Piggin wrote: > > >>For the TLB issue, higher order pagecache doesn't help. If distros >>ship with a 4K page size on powerpc, and use some larger pages in >>the pagecache, some people are still going to get angry because >>they wanted to use 64K pages... But I agree 64K pages is too big >>for most things anyway, and 16 would be better as a default (which >>hopefully x86-64 will get one day). > > > Powerpc supports multiple pagesizes. Maybe we could make mmap use those > page sizes some day if we had a variable order page cache. Your stands on > the issue means that powerpc will be forever crippled and not be able to > use its full potential.
Linus's favourite jokes about powerpc mmu being crippled forever, aside ;)
This seems like just speculation. I would not be against something which, without, would "cripple" some relevant hardware, but you are just handwaving at this point. And you are still ignoring the alternatives.
>>Anyway, for io performance, there are alternatives, dispite what >>some people seem to be saying. We can submit larger sglists to the >>device for larger ios, which Jens is looking at (which could help >>all types of workloads, not just those with sequential large file >>IO). > > > Right this could help but it is not addressing the basic requirement for > devices that need large contiguuos chunks of memory for I/O.
Did you read the last paragraph? Or anything Andrew's been writing?
"After that, I'd find it amusing if HBAs worth thousands of $ have trouble looking up sglists at the relatively glacial pace that IO requires, and/or can't spare a few more K for reasonable sglist sizes, but if that is really the case, then we could use iommus and/or just attempt to put physically contiguous pages in pagecache, rather than require it."
-- SUSE Labs, Novell Inc. - To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
| |