Commit 600e17b2 authored by Alex Bennée's avatar Alex Bennée Committed by Richard Henderson
Browse files

accel/tcg: increase default code gen buffer size for 64 bit 



While 32mb is certainly usable a full system boot ends up flushing the
codegen buffer nearly 100 times. Increase the default on 64 bit hosts
to take advantage of all that spare memory. After this change I can
boot my tests system without any TB flushes.

As we usually run more CONFIG_USER binaries at a time in typical usage
we aren't quite as profligate for user-mode code generation usage. We
also bring the static code gen defies to the same place to keep all
the reasoning in the comments together.

Signed-off-by: default avatarAlex Bennée <alex.bennee@linaro.org>
Tested-by: default avatarNiek Linnenbank <nieklinnenbank@gmail.com>
Reviewed-by: default avatarNiek Linnenbank <nieklinnenbank@gmail.com>
Message-Id: <20200228192415.19867-5-alex.bennee@linaro.org>
Signed-off-by: default avatarRichard Henderson <richard.henderson@linaro.org>
parent 21f2f447

accel/tcg/translate-all.c

+26 −9
Original line number Diff line number Diff line
@@ -892,15 +892,6 @@ static void page_lock_pair(PageDesc **ret_p1, tb_page_addr_t phys1, 
    }

}



#if defined(CONFIG_USER_ONLY) && TCG_TARGET_REG_BITS == 32

/*

 * For user mode on smaller 32 bit systems we may run into trouble

 * allocating big chunks of data in the right place. On these systems

 * we utilise a static code generation buffer directly in the binary.

 */

#define USE_STATIC_CODE_GEN_BUFFER

#endif



/* Minimum size of the code gen buffer.  This number is randomly chosen,

   but not so small that we can't have a fair number of TB's live.  */

#define MIN_CODE_GEN_BUFFER_SIZE     (1 * MiB)
@@ -929,7 +920,33 @@ static void page_lock_pair(PageDesc **ret_p1, tb_page_addr_t phys1, 
# define MAX_CODE_GEN_BUFFER_SIZE  ((size_t)-1)

#endif



#if TCG_TARGET_REG_BITS == 32

#define DEFAULT_CODE_GEN_BUFFER_SIZE_1 (32 * MiB)

#ifdef CONFIG_USER_ONLY

/*

 * For user mode on smaller 32 bit systems we may run into trouble

 * allocating big chunks of data in the right place. On these systems

 * we utilise a static code generation buffer directly in the binary.

 */

#define USE_STATIC_CODE_GEN_BUFFER

#endif

#else /* TCG_TARGET_REG_BITS == 64 */

#ifdef CONFIG_USER_ONLY

/*

 * As user-mode emulation typically means running multiple instances

 * of the translator don't go too nuts with our default code gen

 * buffer lest we make things too hard for the OS.

 */

#define DEFAULT_CODE_GEN_BUFFER_SIZE_1 (128 * MiB)

#else

/*

 * We expect most system emulation to run one or two guests per host.

 * Users running large scale system emulation may want to tweak their

 * runtime setup via the tb-size control on the command line.

 */

#define DEFAULT_CODE_GEN_BUFFER_SIZE_1 (1 * GiB)

#endif

#endif



#define DEFAULT_CODE_GEN_BUFFER_SIZE \

  (DEFAULT_CODE_GEN_BUFFER_SIZE_1 < MAX_CODE_GEN_BUFFER_SIZE \