From: Szabolcs Nagy <szabolcs.nagy@arm.com>
To: libc-alpha@sourceware.org, DJ Delorie <dj@redhat.com>
Subject: [PATCH 0/6] malloc: more memory tagging optimizations
Date: Fri, 19 Mar 2021 13:25:45 +0000 [thread overview]
Message-ID: <cover.1616155129.git.szabolcs.nagy@arm.com> (raw)
Second set of refactoring patches on top of the previously posted
patches. The two sets together are in the nsz/mtag-2 branch.
The main changes are renaming CHUNK_AVAILABLE_SIZE and changing
chunk2mem to not get the tag at mem (so the returned pointer
is not suitable for dereference if mem is already tagged, but
that turns out to be rare).
Further changes considered but rejected:
- remove tag_at from mem2chunk too (mem is often known to be
untagged, or we can assume the internal tag is 0 and turn
tag_at into an unmask operations). this does not seem to have
much performance effect on small allocations.
- don't try to use a new tag different from the old one in
tag_new_usable since at most call sites the old one is just
the internal one which is excluded already from tag generation,
only realloc benefits from the current behaviour. this change
would be a bit aarch64 specific (tag generation can exclude the
internally used tag) and does not have much perf effect either.
Szabolcs Nagy (6):
malloc: Use memsize instead of CHUNK_AVAILABLE_SIZE
malloc: Use different tag after mremap
malloc: Use chunk2rawmem throughout
malloc: Rename chunk2rawmem
malloc: Remove unnecessary tagging around _mid_memalign
malloc: Ensure mtag code path in checked_request2size is cold
malloc/hooks.c | 13 +++--
malloc/malloc.c | 126 +++++++++++++++++++++++++-----------------------
2 files changed, 72 insertions(+), 67 deletions(-)
--
2.17.1
next reply other threads:[~2021-03-19 13:26 UTC|newest]
Thread overview: 13+ messages / expand[flat|nested] mbox.gz Atom feed top
2021-03-19 13:25 Szabolcs Nagy [this message]
2021-03-19 13:26 ` [PATCH 1/6] malloc: Use memsize instead of CHUNK_AVAILABLE_SIZE Szabolcs Nagy
2021-03-23 20:01 ` DJ Delorie
2021-03-19 13:26 ` [PATCH 2/6] malloc: Use different tag after mremap Szabolcs Nagy
2021-03-23 20:03 ` DJ Delorie
2021-03-19 13:26 ` [PATCH 3/6] malloc: Use chunk2rawmem throughout Szabolcs Nagy
2021-03-23 20:25 ` DJ Delorie
2021-03-19 13:27 ` [PATCH 4/6] malloc: Rename chunk2rawmem Szabolcs Nagy
2021-03-23 20:43 ` DJ Delorie
2021-03-19 13:27 ` [PATCH 5/6] malloc: Remove unnecessary tagging around _mid_memalign Szabolcs Nagy
2021-03-23 20:44 ` DJ Delorie
2021-03-19 13:27 ` [PATCH 6/6] malloc: Ensure mtag code path in checked_request2size is cold Szabolcs Nagy
2021-03-23 20:46 ` DJ Delorie
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