On Fri, 16 Mar 2007, David Miller wrote: > From: Christoph Lameter <[EMAIL PROTECTED]> > Date: Fri, 16 Mar 2007 13:52:18 -0700 (PDT) > > > Virtual mmap allows holes in the same way as page tables do. > > I don't want to take expensive TLB misses to lookup a page.
Ummm. You are missing key details please look at linux-mm. We will use huge tlb entries for the mmap and its optional. > TLB misses are extremely expensive on some platforms, that's why > I try to make all the critical structures go through the 4MB > locked TLB entry for the kernel image, or failing that the > 4MB linear mappings at PAGE_OFFSET on sparc64. Exactly. That is why 16M TLB entries speed up the kernel by 4-5% using vmmemmap on ia64. Basically we end up with one TLB per node for the vmemmap which always stays in the cache. No additional lookups. Without vmemmap we still need a 16M TLB for the 1-1 kernel mapping. This jsut cuts out the crud from sparsemem. - 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/
