tcmalloc: Always use a 3 level page map on 64-bit systems.

The memory.desktop benchmark results show a measurable increase in memory
use with a 2-level page map, while no statistically significant performance
gains could be measured by the crosbolt performance tests.

BUG=724399,b:70905156

Change-Id: I566d476851e3d0c964c5f219e4a8277f91a5cbb3
Reviewed-on: https://chromium-review.googlesource.com/c/1130813
Reviewed-by: Will Harris <wfh@chromium.org>
Commit-Queue: Gabriel Marin <gmx@chromium.org>
Cr-Original-Commit-Position: refs/heads/master@{#598012}
Cr-Mirrored-From: https://chromium.googlesource.com/chromium/src
Cr-Mirrored-Commit: 7f8affc6e771fb6ab0c29fda87491adb06669b3f
1 file changed
tree: a5ee8391bcd55801996fe1717583eed564a6a7fa
  1. src/