Re: increased translation cache footprint in v2.6

Andrew Morton
2005-06-26T23:50:38Z

Marcelo Tosatti <marcelo.tosatti@cyclades.com> wrote:
>
> As can be seen the number of entries is more than twice (dominated by kernel addresses).

But doesn't this:

I-TLB userspace misses: 142369 I-TLB userspace misses: 2179 ITLB u: 139190
I-TLB kernel misses: 118288 I-TLB kernel misses: 1369 ITLB k: 116319
D-TLB userspace misses: 222916 D-TLB userspace misses: 180249 DTLB u: 38667
D-TLB kernel misses: 207773 D-TLB kernel misses: 167236 DTLB k: 38273

mean that we're mainly missing on data accesses?

> Sorry, I've got no list of functions for these addresses, but it was pretty obvious at the time
> looking at the sys_read() codepath and respective virtual addresses.
>
> Manual reorganization of the functions sounded too messy, although BenL mentions something about
> fget_light() can and should be optimized.

The workload you're using also does write(), and the write() paths got
significantly deeper.

Stack misses, perhaps. But a tlb entry caches the translation for a single
page, yes?