On Fri, Jul 17, 2020 at 12:51 PM Alex Bennée <alex.ben...@linaro.org> wrote:
> It turns out there are some 64 bit systems that have relatively low
> amounts of physical memory available to them (typically CI system).
> Even with swapping available a 1GB translation buffer that fills up
> can put the machine under increased memory pressure. Detect these low
> memory situations and reduce tb_size appropriately.
>
> Fixes: 600e17b261
> Signed-off-by: Alex Bennée <alex.ben...@linaro.org>
> Cc: BALATON Zoltan <bala...@eik.bme.hu>
> Cc: Christian Ehrhardt <christian.ehrha...@canonical.com>
> ---
> accel/tcg/translate-all.c | 7 ++++++-
> 1 file changed, 6 insertions(+), 1 deletion(-)
>
> diff --git a/accel/tcg/translate-all.c b/accel/tcg/translate-all.c
> index 2afa46bd2b1..2ff0ba6d19b 100644
> --- a/accel/tcg/translate-all.c
> +++ b/accel/tcg/translate-all.c
> @@ -976,7 +976,12 @@ static inline size_t size_code_gen_buffer(size_t
> tb_size)
> {
> /* Size the buffer. */
> if (tb_size == 0) {
> - tb_size = DEFAULT_CODE_GEN_BUFFER_SIZE;
> + size_t phys_mem = qemu_get_host_physmem();
> + if (phys_mem > 0 && phys_mem < (2 *
> DEFAULT_CODE_GEN_BUFFER_SIZE)) {
> + tb_size = phys_mem / 4;
>
In my experiments I've found that /8 more closely matches the former
behavior
on small hosts while at the same time not affecting common large hosts.
> + } else {
> + tb_size = DEFAULT_CODE_GEN_BUFFER_SIZE;
> + }
> }
> if (tb_size < MIN_CODE_GEN_BUFFER_SIZE) {
> tb_size = MIN_CODE_GEN_BUFFER_SIZE;
> --
> 2.20.1
>
>
--
Christian Ehrhardt
Staff Engineer, Ubuntu Server
Canonical Ltd
