From: Richard Henderson <richard.henderson@linaro.org>
To: qemu-devel@nongnu.org
Cc: r.bolshakov@yadro.com, j@getutm.app
Subject: [PATCH v2 18/29] tcg: Tidy tcg_n_regions
Date: Sun, 14 Mar 2021 15:27:13 -0600 [thread overview]
Message-ID: <20210314212724.1917075-19-richard.henderson@linaro.org> (raw)
In-Reply-To: <20210314212724.1917075-1-richard.henderson@linaro.org>
Compute the value using straight division and bounds,
rather than a loop. Pass in tb_size rather than reading
from tcg_init_ctx.code_gen_buffer_size,
Signed-off-by: Richard Henderson <richard.henderson@linaro.org>
---
tcg/region.c | 29 ++++++++++++-----------------
1 file changed, 12 insertions(+), 17 deletions(-)
diff --git a/tcg/region.c b/tcg/region.c
index 23261561a1..23b3459c61 100644
--- a/tcg/region.c
+++ b/tcg/region.c
@@ -363,38 +363,33 @@ void tcg_region_reset_all(void)
tcg_region_tree_reset_all();
}
-static size_t tcg_n_regions(unsigned max_cpus)
+static size_t tcg_n_regions(size_t tb_size, unsigned max_cpus)
{
#ifdef CONFIG_USER_ONLY
return 1;
#else
+ size_t n_regions;
+
/*
* 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;
-
/* Use a single region if all we have is one vCPU thread */
if (max_cpus == 1 || !qemu_tcg_mttcg_enabled()) {
return 1;
}
- /* Try to have more regions than max_cpus, with each region being >= 2 MB */
- for (i = 8; i > 0; i--) {
- size_t regions_per_thread = i;
- size_t region_size;
-
- region_size = tcg_init_ctx.code_gen_buffer_size;
- region_size /= max_cpus * regions_per_thread;
-
- if (region_size >= 2 * 1024u * 1024) {
- return max_cpus * regions_per_thread;
- }
+ /*
+ * Try to have more regions than max_cpus, with each region being >= 2 MB.
+ * If we can't, then just allocate one region per vCPU thread.
+ */
+ n_regions = tb_size / (2 * MiB);
+ if (n_regions <= max_cpus) {
+ return max_cpus;
}
- /* If we can't, then just allocate one region per vCPU thread */
- return max_cpus;
+ return MIN(n_regions, max_cpus * 8);
#endif
}
@@ -829,7 +824,7 @@ void tcg_region_init(size_t tb_size, int splitwx, unsigned max_cpus)
buf = tcg_init_ctx.code_gen_buffer;
total_size = tcg_init_ctx.code_gen_buffer_size;
page_size = qemu_real_host_page_size;
- n_regions = tcg_n_regions(max_cpus);
+ n_regions = tcg_n_regions(total_size, max_cpus);
/* The first region will be 'aligned - buf' bytes larger than the others */
aligned = QEMU_ALIGN_PTR_UP(buf, page_size);
--
2.25.1
next prev parent reply other threads:[~2021-03-14 21:50 UTC|newest]
Thread overview: 38+ messages / expand[flat|nested] mbox.gz Atom feed top
2021-03-14 21:26 [PATCH v2 00/29] tcg: Workaround macOS 11.2 mprotect bug Richard Henderson
2021-03-14 21:26 ` [PATCH v2 01/29] meson: Split out tcg/meson.build Richard Henderson
2021-03-15 23:09 ` Roman Bolshakov
2021-03-14 21:26 ` [PATCH v2 02/29] meson: Split out fpu/meson.build Richard Henderson
2021-03-15 23:10 ` Roman Bolshakov
2021-03-14 21:26 ` [PATCH v2 03/29] tcg: Re-order tcg_region_init vs tcg_prologue_init Richard Henderson
2021-03-15 23:37 ` Roman Bolshakov
2021-03-16 14:57 ` Richard Henderson
2021-03-14 21:26 ` [PATCH v2 04/29] tcg: Remove error return from tcg_region_initial_alloc__locked Richard Henderson
2021-03-14 21:27 ` [PATCH v2 05/29] tcg: Split out tcg_region_initial_alloc Richard Henderson
2021-03-14 21:27 ` [PATCH v2 06/29] tcg: Split out tcg_region_prologue_set Richard Henderson
2021-03-14 21:27 ` [PATCH v2 07/29] tcg: Split out region.c Richard Henderson
2021-03-14 21:27 ` [PATCH v2 08/29] accel/tcg: Inline cpu_gen_init Richard Henderson
2021-03-14 21:27 ` [PATCH v2 09/29] accel/tcg: Move alloc_code_gen_buffer to tcg/region.c Richard Henderson
2021-03-14 21:27 ` [PATCH v2 10/29] accel/tcg: Rename tcg_init to tcg_init_machine Richard Henderson
2021-03-14 21:27 ` [PATCH v2 11/29] tcg: Create tcg_init Richard Henderson
2021-03-14 21:27 ` [PATCH v2 12/29] accel/tcg: Merge tcg_exec_init into tcg_init_machine Richard Henderson
2021-03-14 21:27 ` [PATCH v2 13/29] accel/tcg: Pass down max_cpus to tcg_init Richard Henderson
2021-03-14 21:27 ` [PATCH v2 14/29] tcg: Introduce tcg_max_ctxs Richard Henderson
2021-03-14 21:27 ` [PATCH v2 15/29] tcg: Move MAX_CODE_GEN_BUFFER_SIZE to tcg-target.h Richard Henderson
2021-03-14 21:27 ` [PATCH v2 16/29] tcg: Replace region.end with region.total_size Richard Henderson
2021-03-14 21:27 ` [PATCH v2 17/29] tcg: Rename region.start to region.after_prologue Richard Henderson
2021-03-14 21:27 ` Richard Henderson [this message]
2021-03-14 21:27 ` [PATCH v2 19/29] tcg: Tidy split_cross_256mb Richard Henderson
2021-03-14 21:27 ` [PATCH v2 20/29] tcg: Move in_code_gen_buffer and tests to region.c Richard Henderson
2021-03-14 21:27 ` [PATCH v2 21/29] tcg: Allocate code_gen_buffer into struct tcg_region_state Richard Henderson
2021-03-14 21:27 ` [PATCH v2 22/29] tcg: Return the map protection from alloc_code_gen_buffer Richard Henderson
2021-03-14 22:04 ` Philippe Mathieu-Daudé
2021-03-14 21:27 ` [PATCH v2 23/29] tcg: Sink qemu_madvise call to common code Richard Henderson
2021-03-14 21:27 ` [PATCH v2 24/29] tcg: Do not set guard pages in the rx buffer Richard Henderson
2021-03-14 21:27 ` [PATCH v2 25/29] util/osdep: Add qemu_mprotect_rw Richard Henderson
2021-03-14 21:27 ` [PATCH v2 26/29] tcg: Round the tb_size default from qemu_get_host_physmem Richard Henderson
2021-03-14 21:27 ` [PATCH v2 27/29] tcg: Merge buffer protection and guard page protection Richard Henderson
2021-03-14 21:27 ` [PATCH v2 28/29] tcg: When allocating for !splitwx, begin with PROT_NONE Richard Henderson
2021-03-14 21:27 ` [PATCH v2 29/29] tcg: Move tcg_init_ctx and tcg_ctx from accel/tcg/ Richard Henderson
2021-03-14 22:00 ` Philippe Mathieu-Daudé
2021-03-14 22:12 ` [PATCH v2 00/29] tcg: Workaround macOS 11.2 mprotect bug no-reply
2021-03-15 23:08 ` Roman Bolshakov
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