From patchwork Mon Oct 25 20:08:33 2021 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Kalesh Singh X-Patchwork-Id: 12582859 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id D08B8C433F5 for ; Mon, 25 Oct 2021 20:23:10 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id BAB6060C4A for ; Mon, 25 Oct 2021 20:23:10 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S237438AbhJYUZc (ORCPT ); Mon, 25 Oct 2021 16:25:32 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:36294 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S236970AbhJYUZ1 (ORCPT ); Mon, 25 Oct 2021 16:25:27 -0400 Received: from mail-yb1-xb49.google.com (mail-yb1-xb49.google.com [IPv6:2607:f8b0:4864:20::b49]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id BEF58C046419 for ; Mon, 25 Oct 2021 13:09:18 -0700 (PDT) Received: by mail-yb1-xb49.google.com with SMTP id x68-20020a25ce47000000b005c198858e6bso2718976ybe.21 for ; Mon, 25 Oct 2021 13:09:18 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=google.com; s=20210112; h=date:in-reply-to:message-id:mime-version:references:subject:from:cc; bh=qfxAeMql9xHTEYMmpB1rCuUFev8nHc9PFMoXaO3GDIc=; b=EeKO10IdeY6lDu9fOw7fCpx0gmtGZlf2kJcFIwdqte99OfmVLo3DwJzGslEqR8Cypp XU4Ep/K4eI+qWolLSvL9PlxeRJ6gEedZK81qYc32Hx91IuPpvMHHZfR8a0N0HLLKyXlw 2Gr93y4gUu0cO4g7WQB3/g8/nFjDXDFeQScnLmDjBmQTDgmBOOrVqqNfnR6V0fMGlOpA q/ZipeBBzgzDvUre6a6KoOwiOeG4H1SoSyBORZTd9wiqn57S1fwQZPsSTd5x2SvqwX2m WC/MW48HCuiLJI82UxAq7ZshC7t0hgquTi/tO3qAr8DPTH+2oQMgIOXF/rJ1xx26HWi0 jBOQ== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20210112; h=x-gm-message-state:date:in-reply-to:message-id:mime-version :references:subject:from:cc; bh=qfxAeMql9xHTEYMmpB1rCuUFev8nHc9PFMoXaO3GDIc=; b=7/6vVj1dnp4ORSJFH2BH0IgjUbzNnPgyq2sGlV2ecvurivOr4uMyiS3H1RpKNaFSrk zSulKi3RxvV7fjf4IPXc6pIRPhd5++LBD3DeW6ml7sIexTVI4TYVVovcoBmkTZZpwU8C PoH7h7cvIfEJwbAUF6k3FvXw7pL5OXeY+fbyplDGJ45uun6P7V5U8k/Ao/th3dFxKXnr gPielinXeO5K/vz7alKRVQd8gPI43AVUq7rNXF8B8tA0Bju/74Xbcqv6nriplwrT/Tx7 AHih4Rc/11+rl/u4pml6xjag4UzmJ1DxYzGwqOV10cTYJnfeBUqCH9mQHMB3cpRUN8v5 0Mig== X-Gm-Message-State: AOAM533JY9SNVT3HPA6+v54P4bFxhijteJa8xH8iYCxVVsTzMlWq5+lw UMXgi13SD1bNgAt+sMTZPtOkRNRvfvumDqdKiA== X-Google-Smtp-Source: ABdhPJxizGuCeDpfyj9RAzRnqQT5ZcPO6lgFxNcYXb4DGT1xB/xP0+BrCl74JRDvjh61LxxJ3C6aSwLOvN7cGm6KVA== X-Received: from kaleshsingh.mtv.corp.google.com ([2620:15c:211:200:b783:5702:523e:d435]) (user=kaleshsingh job=sendgmr) by 2002:a25:3082:: with SMTP id w124mr19944249ybw.6.1635192557993; Mon, 25 Oct 2021 13:09:17 -0700 (PDT) Date: Mon, 25 Oct 2021 13:08:33 -0700 In-Reply-To: <20211025200852.3002369-1-kaleshsingh@google.com> Message-Id: <20211025200852.3002369-2-kaleshsingh@google.com> Mime-Version: 1.0 References: <20211025200852.3002369-1-kaleshsingh@google.com> X-Mailer: git-send-email 2.33.0.1079.g6e70778dc9-goog Subject: [PATCH v4 1/8] tracing: Add support for creating hist trigger variables from literal From: Kalesh Singh Cc: surenb@google.com, hridya@google.com, namhyung@kernel.org, kernel-team@android.com, Kalesh Singh , Jonathan Corbet , Steven Rostedt , Ingo Molnar , Shuah Khan , Masami Hiramatsu , Tom Zanussi , linux-doc@vger.kernel.org, linux-kernel@vger.kernel.org, linux-kselftest@vger.kernel.org To: unlisted-recipients:; (no To-header on input) Precedence: bulk List-ID: X-Mailing-List: linux-kselftest@vger.kernel.org Currently hist trigger expressions don't support the use of numeric literals: e.g. echo 'hist:keys=common_pid:x=$y-1234' --> is not valid expression syntax Having the ability to use numeric constants in hist triggers supports a wider range of expressions for creating variables. Add support for creating trace event histogram variables from numeric literals. e.g. echo 'hist:keys=common_pid:x=1234,y=size-1024' >> event/trigger A negative numeric constant is created, using unary minus operator (parentheses are required). e.g. echo 'hist:keys=common_pid:z=-(2)' >> event/trigger Constants can be used with division/multiplication (added in the next patch in this series) to implement granularity filters for frequent trace events. For instance we can limit emitting the rss_stat trace event to when there is a 512KB cross over in the rss size: # Create a synthetic event to monitor instead of the high frequency # rss_stat event echo 'rss_stat_throttled unsigned int mm_id; unsigned int curr; int member; long size' >> tracing/synthetic_events # Create a hist trigger that emits the synthetic rss_stat_throttled # event only when the rss size crosses a 512KB boundary. echo 'hist:keys=keys=mm_id,member:bucket=size/0x80000:onchange($bucket) .rss_stat_throttled(mm_id,curr,member,size)' >> events/kmem/rss_stat/trigger A use case for using constants with addition/subtraction is not yet known, but for completeness the use of constants are supported for all operators. Signed-off-by: Kalesh Singh --- Changes in v3: - Remove the limit on the number of constants that can be created, per Steven Rostedt Changes in v2: - Add description of use case for constants in arithmetic operations in commit message, per Steven Rostedt - Add Namhyung's Reviewed-by kernel/trace/trace_events_hist.c | 71 +++++++++++++++++++++++++++++++- 1 file changed, 70 insertions(+), 1 deletion(-) diff --git a/kernel/trace/trace_events_hist.c b/kernel/trace/trace_events_hist.c index f01e442716e2..28f711224944 100644 --- a/kernel/trace/trace_events_hist.c +++ b/kernel/trace/trace_events_hist.c @@ -66,7 +66,8 @@ C(EMPTY_SORT_FIELD, "Empty sort field"), \ C(TOO_MANY_SORT_FIELDS, "Too many sort fields (Max = 2)"), \ C(INVALID_SORT_FIELD, "Sort field must be a key or a val"), \ - C(INVALID_STR_OPERAND, "String type can not be an operand in expression"), + C(INVALID_STR_OPERAND, "String type can not be an operand in expression"), \ + C(EXPECT_NUMBER, "Expecting numeric literal"), #undef C #define C(a, b) HIST_ERR_##a @@ -89,6 +90,7 @@ typedef u64 (*hist_field_fn_t) (struct hist_field *field, #define HIST_FIELD_OPERANDS_MAX 2 #define HIST_FIELDS_MAX (TRACING_MAP_FIELDS_MAX + TRACING_MAP_VARS_MAX) #define HIST_ACTIONS_MAX 8 +#define HIST_CONST_DIGITS_MAX 21 enum field_op_id { FIELD_OP_NONE, @@ -152,6 +154,9 @@ struct hist_field { bool read_once; unsigned int var_str_idx; + + /* Numeric literals are represented as u64 */ + u64 constant; }; static u64 hist_field_none(struct hist_field *field, @@ -163,6 +168,15 @@ static u64 hist_field_none(struct hist_field *field, return 0; } +static u64 hist_field_const(struct hist_field *field, + struct tracing_map_elt *elt, + struct trace_buffer *buffer, + struct ring_buffer_event *rbe, + void *event) +{ + return field->constant; +} + static u64 hist_field_counter(struct hist_field *field, struct tracing_map_elt *elt, struct trace_buffer *buffer, @@ -341,6 +355,7 @@ enum hist_field_flags { HIST_FIELD_FL_CPU = 1 << 15, HIST_FIELD_FL_ALIAS = 1 << 16, HIST_FIELD_FL_BUCKET = 1 << 17, + HIST_FIELD_FL_CONST = 1 << 18, }; struct var_defs { @@ -1516,6 +1531,12 @@ static void expr_field_str(struct hist_field *field, char *expr) { if (field->flags & HIST_FIELD_FL_VAR_REF) strcat(expr, "$"); + else if (field->flags & HIST_FIELD_FL_CONST) { + char str[HIST_CONST_DIGITS_MAX]; + + snprintf(str, HIST_CONST_DIGITS_MAX, "%llu", field->constant); + strcat(expr, str); + } strcat(expr, hist_field_name(field, 0)); @@ -1689,6 +1710,15 @@ static struct hist_field *create_hist_field(struct hist_trigger_data *hist_data, goto out; } + if (flags & HIST_FIELD_FL_CONST) { + hist_field->fn = hist_field_const; + hist_field->size = sizeof(u64); + hist_field->type = kstrdup("u64", GFP_KERNEL); + if (!hist_field->type) + goto free; + goto out; + } + if (flags & HIST_FIELD_FL_STACKTRACE) { hist_field->fn = hist_field_none; goto out; @@ -2090,6 +2120,29 @@ static struct hist_field *create_alias(struct hist_trigger_data *hist_data, return alias; } +static struct hist_field *parse_const(struct hist_trigger_data *hist_data, + char *str, char *var_name, + unsigned long *flags) +{ + struct trace_array *tr = hist_data->event_file->tr; + struct hist_field *field = NULL; + u64 constant; + + if (kstrtoull(str, 0, &constant)) { + hist_err(tr, HIST_ERR_EXPECT_NUMBER, errpos(str)); + return NULL; + } + + *flags |= HIST_FIELD_FL_CONST; + field = create_hist_field(hist_data, NULL, *flags, var_name); + if (!field) + return NULL; + + field->constant = constant; + + return field; +} + static struct hist_field *parse_atom(struct hist_trigger_data *hist_data, struct trace_event_file *file, char *str, unsigned long *flags, char *var_name) @@ -2100,6 +2153,15 @@ static struct hist_field *parse_atom(struct hist_trigger_data *hist_data, unsigned long buckets = 0; int ret = 0; + if (isdigit(str[0])) { + hist_field = parse_const(hist_data, str, var_name, flags); + if (!hist_field) { + ret = -EINVAL; + goto out; + } + return hist_field; + } + s = strchr(str, '.'); if (s) { s = strchr(++s, '.'); @@ -4950,6 +5012,8 @@ static void hist_field_debug_show_flags(struct seq_file *m, if (flags & HIST_FIELD_FL_ALIAS) seq_puts(m, " HIST_FIELD_FL_ALIAS\n"); + else if (flags & HIST_FIELD_FL_CONST) + seq_puts(m, " HIST_FIELD_FL_CONST\n"); } static int hist_field_debug_show(struct seq_file *m, @@ -4971,6 +5035,9 @@ static int hist_field_debug_show(struct seq_file *m, field->var.idx); } + if (field->flags & HIST_FIELD_FL_CONST) + seq_printf(m, " constant: %llu\n", field->constant); + if (field->flags & HIST_FIELD_FL_ALIAS) seq_printf(m, " var_ref_idx (into hist_data->var_refs[]): %u\n", field->var_ref_idx); @@ -5213,6 +5280,8 @@ static void hist_field_print(struct seq_file *m, struct hist_field *hist_field) if (hist_field->flags & HIST_FIELD_FL_CPU) seq_puts(m, "common_cpu"); + else if (hist_field->flags & HIST_FIELD_FL_CONST) + seq_printf(m, "%llu", hist_field->constant); else if (field_name) { if (hist_field->flags & HIST_FIELD_FL_VAR_REF || hist_field->flags & HIST_FIELD_FL_ALIAS)