diff options
| author | njoly <njoly@NetBSD.org> | 2011-02-26 23:27:49 +0000 |
|---|---|---|
| committer | njoly <njoly@NetBSD.org> | 2011-02-26 23:27:49 +0000 |
| commit | 4ece526c948226dfa5c6a73deca32defe6674aa9 (patch) | |
| tree | fd05d79d70ec510c12e7a58377b28a239e32d805 /lib/libc/stdlib/jemalloc.c | |
| parent | 26868e409e4d53ace21a4784e6162ad8f44120ff (diff) | |
Switch from floating point to fixed point integer for run sizes maths.
From FreeBSD (part of revision 1.154).
Diffstat (limited to 'lib/libc/stdlib/jemalloc.c')
| -rw-r--r-- | lib/libc/stdlib/jemalloc.c | 39 |
1 files changed, 21 insertions, 18 deletions
diff --git a/lib/libc/stdlib/jemalloc.c b/lib/libc/stdlib/jemalloc.c index d01327a7459..cda8500e3e0 100644 --- a/lib/libc/stdlib/jemalloc.c +++ b/lib/libc/stdlib/jemalloc.c @@ -1,4 +1,4 @@ -/* $NetBSD: jemalloc.c,v 1.21 2010/03/04 22:48:31 enami Exp $ */ +/* $NetBSD: jemalloc.c,v 1.22 2011/02/26 23:27:49 njoly Exp $ */ /*- * Copyright (C) 2006,2007 Jason Evans <jasone@FreeBSD.org>. @@ -118,7 +118,7 @@ #include <sys/cdefs.h> /* __FBSDID("$FreeBSD: src/lib/libc/stdlib/malloc.c,v 1.147 2007/06/15 22:00:16 jasone Exp $"); */ -__RCSID("$NetBSD: jemalloc.c,v 1.21 2010/03/04 22:48:31 enami Exp $"); +__RCSID("$NetBSD: jemalloc.c,v 1.22 2011/02/26 23:27:49 njoly Exp $"); #ifdef __FreeBSD__ #include "libc_private.h" @@ -319,20 +319,25 @@ __strerror_r(int e, char *s, size_t l) #define SMALL_MAX_DEFAULT (1 << SMALL_MAX_2POW_DEFAULT) /* - * Maximum desired run header overhead. Runs are sized as small as possible - * such that this setting is still honored, without violating other constraints. - * The goal is to make runs as small as possible without exceeding a per run - * external fragmentation threshold. + * RUN_MAX_OVRHD indicates maximum desired run header overhead. Runs are sized + * as small as possible such that this setting is still honored, without + * violating other constraints. The goal is to make runs as small as possible + * without exceeding a per run external fragmentation threshold. * - * Note that it is possible to set this low enough that it cannot be honored - * for some/all object sizes, since there is one bit of header overhead per - * object (plus a constant). In such cases, this constraint is relaxed. + * We use binary fixed point math for overhead computations, where the binary + * point is implicitly RUN_BFP bits to the left. * - * RUN_MAX_OVRHD_RELAX specifies the maximum number of bits per region of - * overhead for which RUN_MAX_OVRHD is relaxed. + * Note that it is possible to set RUN_MAX_OVRHD low enough that it cannot be + * honored for some/all object sizes, since there is one bit of header overhead + * per object (plus a constant). This constraint is relaxed (ignored) for runs + * that are so small that the per-region overhead is greater than: + * + * (RUN_MAX_OVRHD / (reg_size << (3+RUN_BFP)) */ -#define RUN_MAX_OVRHD 0.015 -#define RUN_MAX_OVRHD_RELAX 1.5 +#define RUN_BFP 12 +/* \/ Implicit binary fixed point. */ +#define RUN_MAX_OVRHD 0x0000003dU +#define RUN_MAX_OVRHD_RELAX 0x00001800U /* Put a cap on small object run size. This overrides RUN_MAX_OVRHD. */ #define RUN_MAX_SMALL_2POW 15 @@ -2143,7 +2148,6 @@ arena_bin_run_size_calc(arena_bin_t *bin, size_t min_run_size) size_t try_run_size, good_run_size; unsigned good_nregs, good_mask_nelms, good_reg0_offset; unsigned try_nregs, try_mask_nelms, try_reg0_offset; - float max_ovrhd = RUN_MAX_OVRHD; assert(min_run_size >= pagesize); assert(min_run_size <= arena_maxclass); @@ -2161,7 +2165,7 @@ arena_bin_run_size_calc(arena_bin_t *bin, size_t min_run_size) */ try_run_size = min_run_size; try_nregs = (unsigned)(((try_run_size - sizeof(arena_run_t)) / - bin->reg_size) + 1); /* Counter-act the first line of the loop. */ + bin->reg_size) + 1); /* Counter-act try_nregs-- in loop. */ do { try_nregs--; try_mask_nelms = (try_nregs >> (SIZEOF_INT_2POW + 3)) + @@ -2195,9 +2199,8 @@ arena_bin_run_size_calc(arena_bin_t *bin, size_t min_run_size) } while (sizeof(arena_run_t) + (sizeof(unsigned) * (try_mask_nelms - 1)) > try_reg0_offset); } while (try_run_size <= arena_maxclass && try_run_size <= RUN_MAX_SMALL - && max_ovrhd > RUN_MAX_OVRHD_RELAX / ((float)(bin->reg_size << 3)) - && ((float)(try_reg0_offset)) / ((float)(try_run_size)) > - max_ovrhd); + && RUN_MAX_OVRHD * (bin->reg_size << 3) > RUN_MAX_OVRHD_RELAX + && (try_reg0_offset << RUN_BFP) > RUN_MAX_OVRHD * try_run_size); assert(sizeof(arena_run_t) + (sizeof(unsigned) * (good_mask_nelms - 1)) <= good_reg0_offset); |
