| commit | a05a920edcf0490529815d77d2d0cc47c121c120 | |
| author | Julian Seward <jseward@acm.org> | |
| Fri, 25 Jan 2019 11:06:37 +0000 (25 12:06 +0100) | ||
| committer | Julian Seward <jseward@acm.org> | |
| Fri, 25 Jan 2019 11:06:37 +0000 (25 12:06 +0100) | ||
| tree | 661ffe7c8518e6452caec470fdc4b0a82a19bf10 | treesnapshot (tar.gz zip) |
| parent | f4072abf6bc9e7791e7b34157fb25210a523dba9 | commitdiff |
VG_(discard_translations): try to avoid invalidating the entire VG_(tt_fast) cache. n-i-bz.
It is very commonly the case that a call to VG_(discard_translations) results
in the discarding of exactly one superblock. In such cases, it's much cheaper
to find and invalidate the VG_(tt_fast) cache entry associated with the block,
than it is to invalidate the entire cache, because
(1) invalidating the fast cache is expensive, and
(2) repopulating the fast cache after invalidation is even more expensive.
For QEMU, which intensively invalidates individual translations (presumably
due to patching them), this reduces the fast-cache miss rate from circa one in
33 lookups to around one in 130 lookups.
It is very commonly the case that a call to VG_(discard_translations) results
in the discarding of exactly one superblock. In such cases, it's much cheaper
to find and invalidate the VG_(tt_fast) cache entry associated with the block,
than it is to invalidate the entire cache, because
(1) invalidating the fast cache is expensive, and
(2) repopulating the fast cache after invalidation is even more expensive.
For QEMU, which intensively invalidates individual translations (presumably
due to patching them), this reduces the fast-cache miss rate from circa one in
33 lookups to around one in 130 lookups.
| coregrind/m_transtab.c | diffblobblamehistory |