Re: Reduce pack-objects memory footprint?
From: Eric Wong <hidden>
Date: 2018-02-28 18:22:38
Duy Nguyen [off-list ref] wrote:
which saves 12 bytes (or another 74 MB). 222 MB total is plenty of space to keep some file cache from being evicted.
Nice! I can definitely benefit from lower memory usage when packing. Fwiw, I use pahole with other projects to help find packing opportunities: git://git.kernel.org/pub/scm/devel/pahole/pahole.git
quoted hunk ↗ jump to hunk
@@ -14,11 +26,10 @@ struct object_entry { void *delta_data; /* cached delta (uncompressed) */ unsigned long delta_size; /* delta data size (uncompressed) */ unsigned long z_delta_size; /* delta data size (compressed) */ - enum object_type type; - enum object_type in_pack_type; /* could be delta */ uint32_t hash; /* name hint hash */ - unsigned int in_pack_pos; unsigned char in_pack_header_size; + unsigned type:3; /* enum object_type */ + unsigned in_pack_type:3; /* enum object_type - could be delta */
For C99 compilers, enums can be bitfields. I introduced the
following macro into Ruby a few weeks ago to remain compatible
with non-C99 compilers:
/*
* For declaring bitfields out of non-unsigned int types:
* struct date {
* BITFIELD(enum months) month:4;
* ...
* };
*/
#if defined(__STDC_VERSION__) && (__STDC_VERSION__ >= 199901L)
# define BITFIELD(type) type
#else
# define BITFIELD(type) unsigned int
#endif