Unverified Commit 07c14672 authored by Oran Agra's avatar Oran Agra Committed by GitHub
Browse files

Set Jemalloc --disable-cache-oblivious to reduce memory overhead (#12315)

Apparently for large size classes Jemalloc allocate some extra
memory (can be up to 25% overhead for allocations of 16kb).
see https://github.com/jemalloc/jemalloc/issues/1098#issuecomment-1589870476

p.s. from Redis's perspective that looks like external fragmentation,
(i.e. allocated bytes will be low, and active pages bytes will be large)
which  can cause active-defrag to eat CPU cycles in vain.

Some details about this mechanism we disable:
---------------------------------------------------------------
Disabling this mechanism only affects large allocations (above 16kb)
Not only that it isn't expected to cause any performance regressions,
it's actually recommended, unless you have a specific workload pattern
and hardware that benefit from this feature -- by default it's enabled and
adds address randomization to all large buffers, by over allocating 1 page
per large size class, and offsetting into that page to mak...
parent 070453ee
......@@ -106,7 +106,7 @@ endif
jemalloc: .make-prerequisites
@printf '%b %b\n' $(MAKECOLOR)MAKE$(ENDCOLOR) $(BINCOLOR)$@$(ENDCOLOR)
cd jemalloc && ./configure --disable-cxx --with-version=5.3.0-0-g0 --with-lg-quantum=3 --with-jemalloc-prefix=je_ CFLAGS="$(JEMALLOC_CFLAGS)" LDFLAGS="$(JEMALLOC_LDFLAGS)" $(JEMALLOC_CONFIGURE_OPTS)
cd jemalloc && ./configure --disable-cxx --with-version=5.3.0-0-g0 --with-lg-quantum=3 --disable-cache-oblivious --with-jemalloc-prefix=je_ CFLAGS="$(JEMALLOC_CFLAGS)" LDFLAGS="$(JEMALLOC_LDFLAGS)" $(JEMALLOC_CONFIGURE_OPTS)
cd jemalloc && $(MAKE) lib/libjemalloc.a
.PHONY: jemalloc
Markdown is supported
0% or .
You are about to add 0 people to the discussion. Proceed with caution.
Finish editing this message first!
Please register or to comment