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[187.189.51.144]) by smtp.gmail.com with ESMTPSA id t2sm9337749qtd.13.2021.03.14.14.27.46 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Sun, 14 Mar 2021 14:27:46 -0700 (PDT) From: Richard Henderson To: qemu-devel@nongnu.org Subject: [PATCH v2 18/29] tcg: Tidy tcg_n_regions Date: Sun, 14 Mar 2021 15:27:13 -0600 Message-Id: <20210314212724.1917075-19-richard.henderson@linaro.org> X-Mailer: git-send-email 2.25.1 In-Reply-To: <20210314212724.1917075-1-richard.henderson@linaro.org> References: <20210314212724.1917075-1-richard.henderson@linaro.org> MIME-Version: 1.0 Received-SPF: pass client-ip=2607:f8b0:4864:20::72a; envelope-from=richard.henderson@linaro.org; helo=mail-qk1-x72a.google.com X-Spam_score_int: -20 X-Spam_score: -2.1 X-Spam_bar: -- X-Spam_report: (-2.1 / 5.0 requ) BAYES_00=-1.9, DKIM_SIGNED=0.1, DKIM_VALID=-0.1, DKIM_VALID_AU=-0.1, DKIM_VALID_EF=-0.1, RCVD_IN_DNSWL_NONE=-0.0001, SPF_HELO_NONE=0.001, SPF_PASS=-0.001 autolearn=ham autolearn_force=no X-Spam_action: no action X-BeenThere: qemu-devel@nongnu.org X-Mailman-Version: 2.1.23 Precedence: list List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Cc: r.bolshakov@yadro.com, j@getutm.app Errors-To: qemu-devel-bounces+qemu-devel=archiver.kernel.org@nongnu.org Sender: "Qemu-devel" 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 --- 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);