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tcg: Adjust CODE_GEN_AVG_BLOCK_SIZE 

At present, the "average" guestimate of TB size is way too small, leading
to many unused entries in the pre-allocated TB array.  For a guest with 1GB
ram, we're currently allocating 256MB for the array.

Survey arm, alpha, aarch64, ppc, sparc, i686, x86_64 guests running on
x86_64 and ppc64 hosts and select a new average.  The size of the array
drops to 81MB with no more flushing than before.

Reviewed-by: Aurelien Jarno <aurelien@aurel32.net>
Signed-off-by: Richard Henderson <rth@twiddle.net>
This commit is contained in:
Richard Henderson 2015-09-26 09:23:42 -07:00
parent b125f9dc7b
commit 126d89e8cd
1 changed files with 6 additions and 5 deletions
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11
include/exec/exec-all.h
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@ -161,13 +161,14 @@ static inline void tlb_flush_by_mmuidx(CPUState *cpu, ...)
#define CODE_GEN_PHYS_HASH_BITS 15
#define CODE_GEN_PHYS_HASH_SIZE (1 << CODE_GEN_PHYS_HASH_BITS)
/* estimated block size for TB allocation */
/* XXX: use a per code average code fragment size and modulate it
according to the host CPU */
/* Estimated block size for TB allocation. */
/* ??? The following is based on a 2015 survey of x86_64 host output.
Better would seem to be some sort of dynamically sized TB array,
adapting to the block sizes actually being produced. */
#if defined(CONFIG_SOFTMMU)
#define CODE_GEN_AVG_BLOCK_SIZE 128
#define CODE_GEN_AVG_BLOCK_SIZE 400
#else
#define CODE_GEN_AVG_BLOCK_SIZE 64
#define CODE_GEN_AVG_BLOCK_SIZE 150
#endif
#if defined(__arm__) || defined(_ARCH_PPC) \