| Message ID | 1443589786-26929-27-git-send-email-rth@twiddle.net |
|---|---|
| State | New |
| Headers | show |
On 2015-09-30 15:09, Richard Henderson wrote: > 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. > > Signed-off-by: Richard Henderson <rth@twiddle.net> > --- > include/exec/exec-all.h | 11 ++++++----- > 1 file changed, 6 insertions(+), 5 deletions(-) Reviewed-by: Aurelien Jarno <aurelien@aurel32.net>
diff --git a/include/exec/exec-all.h b/include/exec/exec-all.h index 71c9d85..a63fd60 100644 --- a/include/exec/exec-all.h +++ b/include/exec/exec-all.h @@ -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) \
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. Signed-off-by: Richard Henderson <rth@twiddle.net> --- include/exec/exec-all.h | 11 ++++++----- 1 file changed, 6 insertions(+), 5 deletions(-)