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Wed, 28 Feb 2024 00:04:14 -0800 (PST) Message-ID: <68b1dff0-13db-4ad0-a1b0-a85991fb3374@linaro.org> Date: Wed, 28 Feb 2024 12:04:10 +0400 MIME-Version: 1.0 User-Agent: Mozilla Thunderbird Subject: Re: [PATCH v5 09/12] contrib/plugins/hotblocks: migrate to new per_vcpu API Content-Language: en-US To: Luc Michel Cc: qemu-devel@nongnu.org, =?UTF-8?Q?Philippe_Mathieu-Daud=C3=A9?= , Richard Henderson , Marcel Apfelbaum , Yanan Wang , Paolo Bonzini , Mahmoud Mandour , Alexandre Iooss , =?UTF-8?Q?Alex_Benn=C3=A9e?= , Eduardo Habkost References: <20240226091446.479436-1-pierrick.bouvier@linaro.org> <20240226091446.479436-10-pierrick.bouvier@linaro.org> From: Pierrick Bouvier In-Reply-To: Content-Type: text/plain; charset=UTF-8; format=flowed Content-Transfer-Encoding: 7bit Received-SPF: pass client-ip=2a00:1450:4864:20::129; envelope-from=pierrick.bouvier@linaro.org; helo=mail-lf1-x129.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, T_SCC_BODY_TEXT_LINE=-0.01, T_SPF_TEMPERROR=0.01 autolearn=ham autolearn_force=no X-Spam_action: no action X-BeenThere: qemu-devel@nongnu.org X-Mailman-Version: 2.1.29 Precedence: list List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Errors-To: qemu-devel-bounces+qemu-devel=archiver.kernel.org@nongnu.org Sender: qemu-devel-bounces+qemu-devel=archiver.kernel.org@nongnu.org On 2/27/24 6:26 PM, Luc Michel wrote: > On 15:09 Tue 27 Feb , Pierrick Bouvier wrote: >> On 2/27/24 2:54 PM, Luc Michel wrote: >>> Hi Pierrick, >>> >>> On 13:14 Mon 26 Feb , Pierrick Bouvier wrote: >>>> Signed-off-by: Pierrick Bouvier >>>> --- >>>> contrib/plugins/hotblocks.c | 50 ++++++++++++++++++++++--------------- >>>> 1 file changed, 30 insertions(+), 20 deletions(-) >>>> >>>> diff --git a/contrib/plugins/hotblocks.c b/contrib/plugins/hotblocks.c >>>> index 4de1b134944..02bc5078bdd 100644 >>>> --- a/contrib/plugins/hotblocks.c >>>> +++ b/contrib/plugins/hotblocks.c >>>> @@ -34,8 +34,8 @@ static guint64 limit = 20; >>>> */ >>>> typedef struct { >>>> uint64_t start_addr; >>>> - uint64_t exec_count; >>>> - int trans_count; >>>> + struct qemu_plugin_scoreboard *exec_count; >>>> + int trans_count; >>>> unsigned long insns; >>>> } ExecCount; >>>> >>>> @@ -43,7 +43,17 @@ static gint cmp_exec_count(gconstpointer a, gconstpointer b) >>>> { >>>> ExecCount *ea = (ExecCount *) a; >>>> ExecCount *eb = (ExecCount *) b; >>>> - return ea->exec_count > eb->exec_count ? -1 : 1; >>>> + uint64_t count_a = >>>> + qemu_plugin_u64_sum(qemu_plugin_scoreboard_u64(ea->exec_count)); >>>> + uint64_t count_b = >>>> + qemu_plugin_u64_sum(qemu_plugin_scoreboard_u64(eb->exec_count)); >>>> + return count_a > count_b ? -1 : 1; >>>> +} >>>> + >>>> +static void exec_count_free(gpointer key, gpointer value, gpointer user_data) >>>> +{ >>>> + ExecCount *cnt = value; >>>> + qemu_plugin_scoreboard_free(cnt->exec_count); >>>> } >>>> >>>> static void plugin_exit(qemu_plugin_id_t id, void *p) >>>> @@ -52,7 +62,6 @@ static void plugin_exit(qemu_plugin_id_t id, void *p) >>>> GList *counts, *it; >>>> int i; >>>> >>>> - g_mutex_lock(&lock); >>> >>> I encountered cases before where the vCPUs continue executing while >>> plugin_exit is called. This can happen e.g., when QEMU calls exit(3) >>> from one CPU thread. Others will continue to run at the same time the >>> atexit callbacks are called. >>> >>> This also means that you can't really free the resources as you do at >>> the end of plugin_exit. >>> >> >> Interesting... >> >> The current documentation [1] mentions it's the right place to free >> resources, and from what I saw, existing plugins assume this too (see >> contrib/plugins/cache.c for instance). >> >> There is probably a bug related to the case you mention, and I'll try to >> reproduce this, and see if we can have a proper fix. >> >> I'm not sure that removing cleanup code from existing plugins is the >> right thing to do at the moment, even though there is an existing issue >> with some programs. > > Yes absolutely. The problem is on the QEMU side. FWIW I tried to fix one > of those exit cases (semihosted exit syscall) some time ago: > https://lore.kernel.org/qemu-devel/20220621125916.25257-1-lmichel@kalray.eu/ > > IIRC Peter was not fundamentally against it. But then I was off for > several months due to medical reasons. > > I can take some time to rebase it and address Peter's comments if there > is interest to it. > It could be well appreciated, and definitely worth fixing! > Luc > >> >> [1] >> https://www.qemu.org/docs/master/devel/tcg-plugins.html#c.qemu_plugin_register_atexit_cb >> >>>> g_string_append_printf(report, "%d entries in the hash table\n", >>>> g_hash_table_size(hotblocks)); >>>> counts = g_hash_table_get_values(hotblocks); >>>> @@ -63,16 +72,21 @@ static void plugin_exit(qemu_plugin_id_t id, void *p) >>>> >>>> for (i = 0; i < limit && it->next; i++, it = it->next) { >>>> ExecCount *rec = (ExecCount *) it->data; >>>> - g_string_append_printf(report, "0x%016"PRIx64", %d, %ld, %"PRId64"\n", >>>> - rec->start_addr, rec->trans_count, >>>> - rec->insns, rec->exec_count); >>>> + g_string_append_printf( >>>> + report, "0x%016"PRIx64", %d, %ld, %"PRId64"\n", >>>> + rec->start_addr, rec->trans_count, >>>> + rec->insns, >>>> + qemu_plugin_u64_sum( >>>> + qemu_plugin_scoreboard_u64(rec->exec_count))); >>>> } >>>> >>>> g_list_free(it); >>>> } >>>> - g_mutex_unlock(&lock); >>>> >>>> qemu_plugin_outs(report->str); >>>> + >>>> + g_hash_table_foreach(hotblocks, exec_count_free, NULL); >>>> + g_hash_table_destroy(hotblocks); >>>> } >>>> >>>> static void plugin_init(void) >>>> @@ -82,15 +96,9 @@ static void plugin_init(void) >>>> >>>> static void vcpu_tb_exec(unsigned int cpu_index, void *udata) >>>> { >>>> - ExecCount *cnt; >>>> - uint64_t hash = (uint64_t) udata; >>>> - >>>> - g_mutex_lock(&lock); >>>> - cnt = (ExecCount *) g_hash_table_lookup(hotblocks, (gconstpointer) hash); >>>> - /* should always succeed */ >>>> - g_assert(cnt); >>>> - cnt->exec_count++; >>>> - g_mutex_unlock(&lock); >>>> + ExecCount *cnt = (ExecCount *)udata; >>>> + qemu_plugin_u64_add(qemu_plugin_scoreboard_u64(cnt->exec_count), >>>> + cpu_index, 1); >>>> } >>>> >>>> /* >>>> @@ -114,18 +122,20 @@ static void vcpu_tb_trans(qemu_plugin_id_t id, struct qemu_plugin_tb *tb) >>>> cnt->start_addr = pc; >>>> cnt->trans_count = 1; >>>> cnt->insns = insns; >>>> + cnt->exec_count = qemu_plugin_scoreboard_new(sizeof(uint64_t)); >>>> g_hash_table_insert(hotblocks, (gpointer) hash, (gpointer) cnt); >>>> } >>>> >>>> g_mutex_unlock(&lock); >>>> >>>> if (do_inline) { >>>> - qemu_plugin_register_vcpu_tb_exec_inline(tb, QEMU_PLUGIN_INLINE_ADD_U64, >>>> - &cnt->exec_count, 1); >>>> + qemu_plugin_register_vcpu_tb_exec_inline_per_vcpu( >>>> + tb, QEMU_PLUGIN_INLINE_ADD_U64, >>>> + qemu_plugin_scoreboard_u64(cnt->exec_count), 1); >>>> } else { >>>> qemu_plugin_register_vcpu_tb_exec_cb(tb, vcpu_tb_exec, >>>> QEMU_PLUGIN_CB_NO_REGS, >>>> - (void *)hash); >>>> + (void *)cnt); >>>> } >>>> } >>>> >>>> -- >>>> 2.43.0 >>>> >>>> >>> >