From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org X-Spam-Level: X-Spam-Status: No, score=-17.7 required=3.0 tests=BAYES_00,DKIMWL_WL_HIGH, DKIM_SIGNED,DKIM_VALID,DKIM_VALID_AU,INCLUDES_CR_TRAILER,INCLUDES_PATCH, MAILING_LIST_MULTI,NICE_REPLY_A,SPF_HELO_NONE,SPF_PASS,URIBL_BLOCKED autolearn=ham autolearn_force=no version=3.4.0 Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id 7033FC6377D for ; Thu, 22 Jul 2021 13:29:29 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 570F760FE7 for ; Thu, 22 Jul 2021 13:29:29 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S232136AbhGVMsx (ORCPT ); Thu, 22 Jul 2021 08:48:53 -0400 Received: from mail.kernel.org ([198.145.29.99]:44112 "EHLO mail.kernel.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S231994AbhGVMsv (ORCPT ); Thu, 22 Jul 2021 08:48:51 -0400 Received: by mail.kernel.org (Postfix) with ESMTPSA id 0270860FED; Thu, 22 Jul 2021 13:29:25 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=k20201202; t=1626960566; bh=GqbPKehGatmKhyx21NjzVmK1K3obNvpO5S2A73limN4=; h=Date:From:To:Cc:Subject:In-Reply-To:References:From; b=hpS88NIfubCj2wLMw36swVruCTadtbPG1fMckI02ULdzx35S4isWp2fLpkRMiWgaR fPjjN1v1JZztJrljeANKsVTCBdx4j0NC4JSUrRt1/cBT1ukaQhYi+N/qgi5zxQZ2oD jYuTJnEMSnQCSrGxWyl554ArAsiygR84gnZlDgiqO0PXrLAPtNUbeOELT0igGo/Lf9 5z0vdwSEsbAUGRdvYMeGxgyzlyOF5ODNnqOGAwkMtg/UsI87deQJn8WobjEH2FcDUT 6wI8TL+8iQoRJOeIg1QHOcblQVcJcPwZet8qyZypx1jtAbmj2rs+DFkoOG95L/NYoU V0P8Gq8L5Rv6Q== Date: Thu, 22 Jul 2021 22:29:24 +0900 From: Masami Hiramatsu To: Steven Rostedt Cc: LKML , Tom Zanussi , Masami Hiramatsu , Namhyung Kim , Ingo Molnar , Andrew Morton Subject: Re: [PATCH v2] tracing: Allow execnames to be passed as args for synthetic events Message-Id: <20210722222924.c4ff024b507c69c08f8575a3@kernel.org> In-Reply-To: <20210721214702.4eeb1cd9@oasis.local.home> References: <20210721214702.4eeb1cd9@oasis.local.home> X-Mailer: Sylpheed 3.7.0 (GTK+ 2.24.32; x86_64-pc-linux-gnu) Mime-Version: 1.0 Content-Type: text/plain; charset=US-ASCII Content-Transfer-Encoding: 7bit Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Wed, 21 Jul 2021 21:47:02 -0400 Steven Rostedt wrote: > From: "Steven Rostedt (VMware)" > > Allow common_pid.execname to be saved in a variable in one histogram to be > passed to another histogram that can pass it as a parameter to a synthetic > event. > > ># echo 'hist:keys=pid:__arg__1=common_timestamp.usecs:arg2=common_pid.execname' \ > > events/sched/sched_waking/trigger > ># echo 'wakeup_lat s32 pid; u64 delta; char wake_comm[]' > synthetic_events > ># echo 'hist:keys=next_pid:pid=next_pid,delta=common_timestamp.usecs-$__arg__1,exec=$arg2'\ > ':onmatch(sched.sched_waking).trace(wakeup_lat,$pid,$delta,$exec)' \ > > events/sched/sched_switch/trigger > > The above is a wake up latency synthetic event setup that passes the execname > of the common_pid that woke the task to the scheduling of that task, which > triggers a synthetic event that passes the original execname as a > parameter to display it. > > ># echo 1 > events/synthetic/enable > ># cat trace > -0 [006] d..4 186.863801: wakeup_lat: pid=1306 delta=65 wake_comm=kworker/u16:3 > -0 [000] d..4 186.863858: wakeup_lat: pid=163 delta=27 wake_comm= > -0 [001] d..4 186.863903: wakeup_lat: pid=1307 delta=36 wake_comm=kworker/u16:4 > -0 [000] d..4 186.863927: wakeup_lat: pid=163 delta=5 wake_comm= > -0 [006] d..4 186.863957: wakeup_lat: pid=1306 delta=24 wake_comm=kworker/u16:3 > sshd-1306 [006] d..4 186.864051: wakeup_lat: pid=61 delta=62 wake_comm= > -0 [000] d..4 186.965030: wakeup_lat: pid=609 delta=18 wake_comm= > -0 [006] d..4 186.987582: wakeup_lat: pid=1306 delta=65 wake_comm=kworker/u16:3 > -0 [000] d..4 186.987639: wakeup_lat: pid=163 delta=27 wake_comm= > This looks an interesting improvement. If we can do this, can we also filter the event by 'comm' (or execname)? > Signed-off-by: Steven Rostedt (VMware) > --- > Changes since v1: > - Hit a bug on freeing the histogram, found that I used "char[]" for the > type, and it expects to be freed. Freed the old "type" and still use > "char[]" but have the normal freeing use kfree_const() on type. BTW, if we can use this technic on the hist_field->type, we can cleanup other type = strdup("", GFP_KERNEL) with type = "" ? Anyway, that will be done in another patch (I think that should be done first, then we can avoid an odd kfree() in update_var_execname().) Thank you, > > kernel/trace/trace_events_hist.c | 49 ++++++++++++++++++++++++++++---- > 1 file changed, 44 insertions(+), 5 deletions(-) > > diff --git a/kernel/trace/trace_events_hist.c b/kernel/trace/trace_events_hist.c > index 34325f41ebc0..bb1956efd5ef 100644 > --- a/kernel/trace/trace_events_hist.c > +++ b/kernel/trace/trace_events_hist.c > @@ -1395,17 +1395,17 @@ static int hist_trigger_elt_data_alloc(struct tracing_map_elt *elt) > struct hist_trigger_data *hist_data = elt->map->private_data; > unsigned int size = TASK_COMM_LEN; > struct hist_elt_data *elt_data; > - struct hist_field *key_field; > + struct hist_field *hist_field; > unsigned int i, n_str; > > elt_data = kzalloc(sizeof(*elt_data), GFP_KERNEL); > if (!elt_data) > return -ENOMEM; > > - for_each_hist_key_field(i, hist_data) { > - key_field = hist_data->fields[i]; > + for_each_hist_field(i, hist_data) { > + hist_field = hist_data->fields[i]; > > - if (key_field->flags & HIST_FIELD_FL_EXECNAME) { > + if (hist_field->flags & HIST_FIELD_FL_EXECNAME) { > elt_data->comm = kzalloc(size, GFP_KERNEL); > if (!elt_data->comm) { > kfree(elt_data); > @@ -1589,7 +1589,9 @@ static void __destroy_hist_field(struct hist_field *hist_field) > > kfree(hist_field->var.name); > kfree(hist_field->name); > - kfree(hist_field->type); > + > + /* execname vars use a constant type */ > + kfree_const(hist_field->type); > > kfree(hist_field->system); > kfree(hist_field->event_name); > @@ -3707,6 +3709,40 @@ static int create_val_field(struct hist_trigger_data *hist_data, > return __create_val_field(hist_data, val_idx, file, NULL, field_str, 0); > } > > +static const char *no_comm = "(no comm)"; > + > +static u64 hist_field_execname(struct hist_field *hist_field, > + struct tracing_map_elt *elt, > + struct trace_buffer *buffer, > + struct ring_buffer_event *rbe, > + void *event) > +{ > + struct hist_elt_data *elt_data; > + > + if (WARN_ON_ONCE(!elt)) > + return (u64)(unsigned long)no_comm; > + > + elt_data = elt->private_data; > + > + if (WARN_ON_ONCE(!elt_data->comm)) > + return (u64)(unsigned long)no_comm; > + > + return (u64)(unsigned long)(elt_data->comm); > +} > + > +/* Convert a var that points to common_pid.execname to a string */ > +static void update_var_execname(struct hist_field *hist_field) > +{ > + hist_field->flags = HIST_FIELD_FL_STRING | HIST_FIELD_FL_VAR | > + HIST_FIELD_FL_EXECNAME; > + hist_field->size = MAX_FILTER_STR_VAL; > + hist_field->is_signed = 0; > + kfree(hist_field->type); > + /* This uses kfree_const() to free */ > + hist_field->type = "char[]"; > + hist_field->fn = hist_field_execname; > +} > + > static int create_var_field(struct hist_trigger_data *hist_data, > unsigned int val_idx, > struct trace_event_file *file, > @@ -3731,6 +3767,9 @@ static int create_var_field(struct hist_trigger_data *hist_data, > > ret = __create_val_field(hist_data, val_idx, file, var_name, expr_str, flags); > > + if (!ret && hist_data->fields[val_idx]->flags & HIST_FIELD_FL_EXECNAME) > + update_var_execname(hist_data->fields[val_idx]); > + > if (!ret && hist_data->fields[val_idx]->flags & HIST_FIELD_FL_STRING) > hist_data->fields[val_idx]->var_str_idx = hist_data->n_var_str++; > > -- > 2.31.1 > -- Masami Hiramatsu