configure: add --with-lg-slab-maxregs configure option.

Specify the maximum number of regions in a slab, which is
(<lg-page> - <lg-tiny-min>) by default. This increases the limit of slab sizes
specified by "slab_sizes" in malloc_conf. This should never be less than
the default value. The max value of this option is related to LG_BITMAP_MAXBITS
(see more in bitmap.h).

For example, on a 4k page size system, if we:
  1) configure jemalloc with with --with-lg-slab-maxregs=12.
  2) export MALLOC_CONF="slab_sizes:9-16:4"
The slab size of 16 bytes is set to 4 pages. Previously, the default
lg-slab-maxregs is 9 (i.e. 12 - 3). The max slab size of 16 bytes is 2 pages
(i.e. (1<<9) * 16 bytes). By increasing the value from 9 to 12, the max slab
size can be set by MALLOC_CONF is 16 pages (i.e. (1<<12) * 16 bytes).
This commit is contained in:
Hao Liu
2020-09-09 12:21:41 +08:00
committed by David Goldblatt
parent d243b4ec48
commit 1541ffc765
4 changed files with 27 additions and 2 deletions

View File

@@ -182,6 +182,9 @@
/* One page is 2^LG_PAGE bytes. */
#undef LG_PAGE
/* Maximum number of regions in a slab. */
#undef LG_SLAB_MAXREGS
/*
* One huge page is 2^LG_HUGEPAGE bytes. Note that this is defined even if the
* system does not explicitly support huge pages; system calls that require

View File

@@ -270,8 +270,14 @@
#define SC_LARGE_MAXCLASS (SC_MAX_BASE + (SC_NGROUP - 1) * SC_MAX_DELTA)
/* Maximum number of regions in one slab. */
#define SC_LG_SLAB_MAXREGS (LG_PAGE - SC_LG_TINY_MIN)
#define SC_SLAB_MAXREGS (1U << LG_SLAB_MAXREGS)
#ifndef LG_SLAB_MAXREGS
# define SC_LG_SLAB_MAXREGS (LG_PAGE - SC_LG_TINY_MIN)
#elif (LG_SLAB_MAXREGS < (LG_PAGE - SC_LG_TINY_MIN))
# error "Unsupported SC_LG_SLAB_MAXREGS"
#else
# define SC_LG_SLAB_MAXREGS LG_SLAB_MAXREGS
#endif
#define SC_SLAB_MAXREGS (1U << SC_LG_SLAB_MAXREGS)
typedef struct sc_s sc_t;