From: "Alex Bennée" <alex.bennee@linaro.org>
To: Richard Henderson <richard.henderson@linaro.org>
Cc: "Philippe Mathieu-Daudé" <f4bug@amsat.org>, qemu-devel@nongnu.org
Subject: Re: [PATCH v3 13/28] accel/tcg: Pass down max_cpus to tcg_init
Date: Tue, 08 Jun 2021 16:44:11 +0100 [thread overview]
Message-ID: <87a6o0l5g2.fsf@linaro.org> (raw)
In-Reply-To: <20210502231844.1977630-14-richard.henderson@linaro.org>
Richard Henderson <richard.henderson@linaro.org> writes:
> Start removing the include of hw/boards.h from tcg/.
> Pass down the max_cpus value from tcg_init_machine,
> where we have the MachineState already.
>
> Reviewed-by: Philippe Mathieu-Daudé <f4bug@amsat.org>
> Signed-off-by: Richard Henderson <richard.henderson@linaro.org>
> ---
<snip>
> -static size_t tcg_n_regions(void)
> -{
> + /*
> + * It is likely that some vCPUs will translate more code than others,
> + * so we first try to set more regions than max_cpus, with those regions
> + * being of reasonable size. If that's not possible we make do by evenly
> + * dividing the code_gen_buffer among the vCPUs.
> + */
> size_t i;
>
heh TIL. That said currently this "fancy" allocation method does nothing
for user-mode code generation which just gets to share one big code gen
buffer.
Thinking aloud I do recall an alternative approach is to have regions
more closely aligned with the guest memory map with a region lock which
any thread can acquire when it needs generate code for the guest region.
In user-mode for example that would be a region per DSO. In system mode
it may be simpler to have the current per-vCPU layout but consider if
all kernel mode code is generated in one buffer and can patch jumps
within that region? Of course any TLB flush that hits code in that
region would force regeneration of all that code but it shouldn't happen
for kernel mode code.
Anyway random musings aside:
Reviewed-by: Alex Bennée <alex.bennee@linaro.org>
--
Alex Bennée
next prev parent reply other threads:[~2021-06-08 15:58 UTC|newest]
Thread overview: 92+ messages / expand[flat|nested] mbox.gz Atom feed top
2021-05-02 23:18 [PATCH v3 00/28] tcg: Clean up code_gen_buffer allocation Richard Henderson
2021-05-02 23:18 ` [PATCH v3 01/28] meson: Split out tcg/meson.build Richard Henderson
2021-06-07 19:38 ` Alex Bennée
2021-06-09 14:56 ` Luis Fernando Fujita Pires
2021-05-02 23:18 ` [PATCH v3 02/28] meson: Split out fpu/meson.build Richard Henderson
2021-06-07 19:38 ` Alex Bennée
2021-06-09 14:57 ` Luis Fernando Fujita Pires
2021-05-02 23:18 ` [PATCH v3 03/28] tcg: Re-order tcg_region_init vs tcg_prologue_init Richard Henderson
2021-06-08 9:04 ` Alex Bennée
2021-06-09 14:57 ` Luis Fernando Fujita Pires
2021-05-02 23:18 ` [PATCH v3 04/28] tcg: Remove error return from tcg_region_initial_alloc__locked Richard Henderson
2021-06-08 11:04 ` Alex Bennée
2021-06-08 15:44 ` Richard Henderson
2021-06-09 14:57 ` Luis Fernando Fujita Pires
2021-05-02 23:18 ` [PATCH v3 05/28] tcg: Split out tcg_region_initial_alloc Richard Henderson
2021-06-08 11:45 ` Alex Bennée
2021-06-09 14:57 ` Luis Fernando Fujita Pires
2021-05-02 23:18 ` [PATCH v3 06/28] tcg: Split out tcg_region_prologue_set Richard Henderson
2021-06-08 11:47 ` Alex Bennée
2021-06-09 14:57 ` Luis Fernando Fujita Pires
2021-05-02 23:18 ` [PATCH v3 07/28] tcg: Split out region.c Richard Henderson
2021-06-08 11:48 ` Alex Bennée
2021-06-09 14:57 ` Luis Fernando Fujita Pires
2021-05-02 23:18 ` [PATCH v3 08/28] accel/tcg: Inline cpu_gen_init Richard Henderson
2021-06-08 11:49 ` Alex Bennée
2021-06-09 14:57 ` Luis Fernando Fujita Pires
2021-05-02 23:18 ` [PATCH v3 09/28] accel/tcg: Move alloc_code_gen_buffer to tcg/region.c Richard Henderson
2021-06-08 11:50 ` Alex Bennée
2021-06-09 14:57 ` Luis Fernando Fujita Pires
2021-05-02 23:18 ` [PATCH v3 10/28] accel/tcg: Rename tcg_init to tcg_init_machine Richard Henderson
2021-06-08 11:51 ` Alex Bennée
2021-06-09 14:57 ` Luis Fernando Fujita Pires
2021-05-02 23:18 ` [PATCH v3 11/28] tcg: Create tcg_init Richard Henderson
2021-06-08 11:52 ` Alex Bennée
2021-06-09 14:57 ` Luis Fernando Fujita Pires
2021-05-02 23:18 ` [PATCH v3 12/28] accel/tcg: Merge tcg_exec_init into tcg_init_machine Richard Henderson
2021-06-08 11:55 ` Alex Bennée
2021-06-08 15:45 ` Richard Henderson
2021-06-09 14:58 ` Luis Fernando Fujita Pires
2021-06-10 15:16 ` Richard Henderson
2021-05-02 23:18 ` [PATCH v3 13/28] accel/tcg: Pass down max_cpus to tcg_init Richard Henderson
2021-06-08 15:44 ` Alex Bennée [this message]
2021-06-09 14:58 ` Luis Fernando Fujita Pires
2021-05-02 23:18 ` [PATCH v3 14/28] tcg: Introduce tcg_max_ctxs Richard Henderson
2021-06-08 15:54 ` Alex Bennée
2021-06-09 14:58 ` Luis Fernando Fujita Pires
2021-05-02 23:18 ` [PATCH v3 15/28] tcg: Move MAX_CODE_GEN_BUFFER_SIZE to tcg-target.h Richard Henderson
2021-06-08 15:56 ` Alex Bennée
2021-06-09 14:58 ` Luis Fernando Fujita Pires
2021-05-02 23:18 ` [PATCH v3 16/28] tcg: Replace region.end with region.total_size Richard Henderson
2021-06-08 16:03 ` Alex Bennée
2021-06-08 16:12 ` Richard Henderson
2021-06-09 14:58 ` Luis Fernando Fujita Pires
2021-05-02 23:18 ` [PATCH v3 17/28] tcg: Rename region.start to region.after_prologue Richard Henderson
2021-06-08 16:06 ` Alex Bennée
2021-06-09 14:58 ` Luis Fernando Fujita Pires
2021-05-02 23:18 ` [PATCH v3 18/28] tcg: Tidy tcg_n_regions Richard Henderson
2021-06-08 16:06 ` Alex Bennée
2021-06-09 14:58 ` Luis Fernando Fujita Pires
2021-05-02 23:18 ` [PATCH v3 19/28] tcg: Tidy split_cross_256mb Richard Henderson
2021-06-09 10:01 ` Alex Bennée
2021-06-09 14:59 ` Luis Fernando Fujita Pires
2021-06-10 15:20 ` Richard Henderson
2021-05-02 23:18 ` [PATCH v3 20/28] tcg: Move in_code_gen_buffer and tests to region.c Richard Henderson
2021-06-09 10:07 ` Alex Bennée
2021-06-09 14:59 ` Luis Fernando Fujita Pires
2021-05-02 23:18 ` [PATCH v3 21/28] tcg: Allocate code_gen_buffer into struct tcg_region_state Richard Henderson
2021-06-09 10:29 ` Alex Bennée
2021-06-09 14:59 ` Luis Fernando Fujita Pires
2021-05-02 23:18 ` [PATCH v3 22/28] tcg: Return the map protection from alloc_code_gen_buffer Richard Henderson
2021-06-09 10:30 ` Alex Bennée
2021-06-09 14:59 ` Luis Fernando Fujita Pires
2021-05-02 23:18 ` [PATCH v3 23/28] tcg: Sink qemu_madvise call to common code Richard Henderson
2021-06-09 10:34 ` Alex Bennée
2021-06-09 14:59 ` Luis Fernando Fujita Pires
2021-05-02 23:18 ` [PATCH v3 24/28] util/osdep: Add qemu_mprotect_rw Richard Henderson
2021-06-09 10:34 ` Alex Bennée
2021-06-09 14:59 ` Luis Fernando Fujita Pires
2021-05-02 23:18 ` [PATCH v3 25/28] tcg: Round the tb_size default from qemu_get_host_physmem Richard Henderson
2021-06-09 10:36 ` Alex Bennée
2021-06-09 14:59 ` Luis Fernando Fujita Pires
2021-05-02 23:18 ` [PATCH v3 26/28] tcg: Merge buffer protection and guard page protection Richard Henderson
2021-06-09 10:39 ` Alex Bennée
2021-06-09 14:59 ` Luis Fernando Fujita Pires
2021-05-02 23:18 ` [PATCH v3 27/28] tcg: When allocating for !splitwx, begin with PROT_NONE Richard Henderson
2021-06-09 11:21 ` Alex Bennée
2021-06-10 15:34 ` Richard Henderson
2021-06-09 14:59 ` Luis Fernando Fujita Pires
2021-05-02 23:18 ` [PATCH v3 28/28] tcg: Move tcg_init_ctx and tcg_ctx from accel/tcg/ Richard Henderson
2021-06-09 11:30 ` Alex Bennée
2021-06-09 14:59 ` Luis Fernando Fujita Pires
2021-05-02 23:45 ` [PATCH v3 00/28] tcg: Clean up code_gen_buffer allocation no-reply
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