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Re: [PATCH v1 4/4] accel/tcg: increase default code gen buffer size for
From: |
Richard Henderson |
Subject: |
Re: [PATCH v1 4/4] accel/tcg: increase default code gen buffer size for 64 bit |
Date: |
Wed, 26 Feb 2020 14:55:36 -0800 |
User-agent: |
Mozilla/5.0 (X11; Linux x86_64; rv:68.0) Gecko/20100101 Thunderbird/68.4.1 |
On 2/26/20 10:10 AM, Alex Bennée wrote:
> 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.
> +#if TCG_TARGET_REG_BITS == 32
> #define DEFAULT_CODE_GEN_BUFFER_SIZE_1 (32 * MiB)
> +#else
> +#define DEFAULT_CODE_GEN_BUFFER_SIZE_1 (2 * GiB)
> +#endif
This particular number, I'm not so sure about.
It makes sense for a lone vm, running in system mode, on a large-ish host.
It's more questionable for a large-ish host running many system mode vm's,
although one can tune that from the command-line, so perhaps it's still ok.
It does not make sense for a linux-user chroot, running make -jN, on just about
any host. For linux-user, I could be happy with a modest increase, but not all
the way out to 2GiB.
Discuss.
r~
- Re: [PATCH v1 2/4] accel/tcg: remove link between guest ram and TCG cache size, (continued)
- [PATCH v1 3/4] accel/tcg: only USE_STATIC_CODE_GEN_BUFFER on 32 bit hosts, Alex Bennée, 2020/02/26
- [PATCH v1 4/4] accel/tcg: increase default code gen buffer size for 64 bit, Alex Bennée, 2020/02/26
- Re: [PATCH v1 4/4] accel/tcg: increase default code gen buffer size for 64 bit,
Richard Henderson <=
- Re: [PATCH v1 4/4] accel/tcg: increase default code gen buffer size for 64 bit, Alex Bennée, 2020/02/27
- Re: [PATCH v1 4/4] accel/tcg: increase default code gen buffer size for 64 bit, Richard Henderson, 2020/02/27
- Re: [PATCH v1 4/4] accel/tcg: increase default code gen buffer size for 64 bit, Igor Mammedov, 2020/02/27
- Re: [PATCH v1 4/4] accel/tcg: increase default code gen buffer size for 64 bit, Niek Linnenbank, 2020/02/27
- Re: [PATCH v1 4/4] accel/tcg: increase default code gen buffer size for 64 bit, Igor Mammedov, 2020/02/28
- Re: [PATCH v1 4/4] accel/tcg: increase default code gen buffer size for 64 bit, Alex Bennée, 2020/02/28
- [PATCH] accel/tcg: increase default code gen buffer size for 64 bit, Alex Bennée, 2020/02/28