From patchwork Mon Feb 12 23:09:41 2024 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Steven Rostedt X-Patchwork-Id: 13554136 Received: from smtp.kernel.org (aws-us-west-2-korg-mail-1.web.codeaurora.org [10.30.226.201]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id 46FB74EB28; Mon, 12 Feb 2024 23:08:59 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=10.30.226.201 ARC-Seal: i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1707779340; cv=none; b=XAFKARQNbqpQyK+pc5uRvh8MeRlsDwNfgEIUUg+tz+ueJK0Jx9t1DOWWHN01TL3gzSu6WVXiOaIMmgxrcIyt/WCcY+xUcBqBszAC4G8Q9pzL1gy3Xgw0KvL+Y5AQwxWPgkb2u/cYdrFnUVVO5F9KL/nwU3drQP3ea9c1/Kd9C3E= ARC-Message-Signature: i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1707779340; c=relaxed/simple; bh=hhDd4Zg33Gyyd3pXps6UXldwu1puK288MZOmI4zYWyY=; h=Date:From:To:Cc:Subject:Message-ID:MIME-Version:Content-Type; b=RQLZUpnbZzj7xFZCjhXbW/fL8rcnwhqZRNMO5xwu1h2H7fNKd2avfylGoQ4njVwRYCoNOm9CUOPdqE9HO4ykv3DM13o9DGFADQBZMMVGw4WgD+4z7co/7mv6kQX40BLdWIdzwOnAQtDMeHwyGkCHX/k2W2imV/wkYYpQdomRL5w= ARC-Authentication-Results: i=1; smtp.subspace.kernel.org; arc=none smtp.client-ip=10.30.226.201 Received: by smtp.kernel.org (Postfix) with ESMTPSA id BC65EC433C7; Mon, 12 Feb 2024 23:08:58 +0000 (UTC) Date: Mon, 12 Feb 2024 18:09:41 -0500 From: Steven Rostedt To: LKML , Linux Trace Kernel Cc: Masami Hiramatsu , Mathieu Desnoyers , Mark Rutland , Tim Chen , Vincent Donnefort , Sven Schnelle , Mete Durlu Subject: [PATCH] tracing: Have saved_cmdlines arrays all in one allocation Message-ID: <20240212180941.379c419b@gandalf.local.home> X-Mailer: Claws Mail 3.19.1 (GTK+ 2.24.33; x86_64-pc-linux-gnu) Precedence: bulk X-Mailing-List: linux-trace-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 From: "Steven Rostedt (Google)" The saved_cmdlines have three arrays for mapping PIDs to COMMs: - map_pid_to_cmdline[] - map_cmdline_to_pid[] - saved_cmdlines The map_pid_to_cmdline[] is PID_MAX_DEFAULT in size and holds the index into the other arrays. The map_cmdline_to_pid[] is a mapping back to the full pid as it can be larger than PID_MAX_DEFAULT. And the saved_cmdlines[] just holds the COMMs associated to the pids. Currently the map_pid_to_cmdline[] and saved_cmdlines[] are allocated together (in reality the saved_cmdlines is just in the memory of the rounding of the allocation of the structure as it is always allocated in powers of two). The map_cmdline_to_pid[] array is allocated separately. Since the rounding to a power of two is rather large (it allows for 8000 elements in saved_cmdlines), also include the map_cmdline_to_pid[] array. (This drops it to 6000 by default, which is still plenty for most use cases). This saves even more memory as the map_cmdline_to_pid[] array doesn't need to be allocated. Link: https://lore.kernel.org/linux-trace-kernel/20240212174011.068211d9@gandalf.local.home/ Signed-off-by: Steven Rostedt (Google) Acked-by: Masami Hiramatsu (Google) Reviewed-by: Tim Chen --- kernel/trace/trace_sched_switch.c | 13 ++++--------- 1 file changed, 4 insertions(+), 9 deletions(-) diff --git a/kernel/trace/trace_sched_switch.c b/kernel/trace/trace_sched_switch.c index e4fbcc3bede5..210c74dcd016 100644 --- a/kernel/trace/trace_sched_switch.c +++ b/kernel/trace/trace_sched_switch.c @@ -201,7 +201,7 @@ static struct saved_cmdlines_buffer *allocate_cmdlines_buffer(unsigned int val) int order; /* Figure out how much is needed to hold the given number of cmdlines */ - orig_size = sizeof(*s) + val * TASK_COMM_LEN; + orig_size = sizeof(*s) + val * (TASK_COMM_LEN + sizeof(int)); order = get_order(orig_size); size = 1 << (order + PAGE_SHIFT); page = alloc_pages(GFP_KERNEL, order); @@ -212,16 +212,11 @@ static struct saved_cmdlines_buffer *allocate_cmdlines_buffer(unsigned int val) memset(s, 0, sizeof(*s)); /* Round up to actual allocation */ - val = (size - sizeof(*s)) / TASK_COMM_LEN; + val = (size - sizeof(*s)) / (TASK_COMM_LEN + sizeof(int)); s->cmdline_num = val; - s->map_cmdline_to_pid = kmalloc_array(val, - sizeof(*s->map_cmdline_to_pid), - GFP_KERNEL); - if (!s->map_cmdline_to_pid) { - free_saved_cmdlines_buffer(s); - return NULL; - } + /* Place map_cmdline_to_pid array right after saved_cmdlines */ + s->map_cmdline_to_pid = (unsigned *)&s->saved_cmdlines[val * TASK_COMM_LEN]; s->cmdline_idx = 0; memset(&s->map_pid_to_cmdline, NO_CMDLINE_MAP,