From mboxrd@z Thu Jan 1 00:00:00 1970 Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.remote-ip=209.85.128.70 ARC-Seal: i=1; d=subspace.kernel.org; s=arc20261015; a=rsa-sha256; cv=none; t=1793988472; b=nw24PHQXrKX7CDlqtc3IjNtmlOSolbR/qQ54SSGbitqR72Co4YaSLnw03tSB9DLWaodU A/vN2DofCti4XPYIQbCNFF4nZarFPkbVERTtIBZCZc9EaPoyLqLoGyGPvUJU9MrEmPOVx Ib9FzZdWUUYaStzApSFgCM/izufzV2GucciBtyI08MH+NQshn/QeYDMLeZ7K71GH1MMgR pAO58VHnI7IlDTwPH75ZdCqXbXcCDaIX93HzFSG1mctmbNHCOwf1QwCq/tVLkeywtNWEF 8PLF6IjfwAFVEP+ts5+OoUho4bm+QDHxNo7ZIj5dnPGjLMxAVHrO8nISkQ68474Z4Ww== ARC-Message-Signature: i=1; d=subspace.kernel.org; s=arc20261015; a=rsa-sha256; c=relaxed/relaxed; t=1793988472; h=DMARC-Filter:Received:DKIM-Signature:X-Google-DKIM-Signature: X-Forwarded-Encrypted:X-Gm-Message-State:X-Received:Date:In-Reply-To: Mime-Version:References:X-Mailer:Message-ID:Subject:From:To:Cc: Content-Type; bh=EuW+q0IZAiSlccInoGG1ZV09yqmS19RZQDDu5PkfcPQ=; b=Tr9ZNSsWMJ6pF2N48yOxL37z5r/YIpWW31iI5epciq+n9Ye/bKRZnnO7yjHGj8A4Z5OO dW/M/G4rxyTAoMceeZb4Dpa1t+MyBmVDDbDS3t9WNwoHbuVLbQE1jw98DjpJIVFPoer1P kqaOpoGC9mUAvGKOxN7rlcW5O4X21L3ZCzgY7+55ZsutmEiaLJl5r2vJ/30KGCh5iyxAD +rNCgzwb2TXQq54wTMNFq5czTbqdc6/K485Hn1gMXs29gzAfnvNAi1ADfjMTscsIXj3aS 03t2rqPVvajyjnQ/ATtEHW3eTBWk0rOToJEMvukm+ZOw2Oe9uAj5A7UVe9CHuWOPcZQ== ARC-Authentication-Results: i=1; smtp.subspace.kernel.org; dmarc=pass header.from=google.com; spf=pass smtp.mailfrom=flex--vdonnefort.bounces.google.com; dkim=pass header.d=google.com header.i=@google.com header.a=rsa-sha256 header.s=20260707 header.b=UDP1eJ+K; arc=none smtp.remote-ip=209.85.128.70 Received: from mail-wm1-f70.google.com (mail-wm1-f70.google.com [209.85.128.70]) (using TLSv1.3 with cipher TLS_AES_128_GCM_SHA256 (128/128 bits) key-exchange X25519 server-signature ECDSA (prime256v1) server-digest SHA256) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id 9631A606A335 for ; Fri, 6 Nov 2026 18:07:52 +0000 (UTC) DMARC-Filter: OpenDMARC Filter v1.4.2 smtp.subspace.kernel.org 9631A606A335 Authentication-Results: smtp.subspace.kernel.org; dmarc=pass (p=reject dis=none) header.from=google.com Authentication-Results: smtp.subspace.kernel.org; spf=pass smtp.mailfrom=flex--vdonnefort.bounces.google.com Authentication-Results: smtp.subspace.kernel.org; dkim=pass (2048-bit key, unprotected) header.d=google.com header.i=@google.com header.a=rsa-sha256 header.s=20260707 header.b=UDP1eJ+K Received: by mail-wm1-f70.google.com with SMTP id 5b1f17b1804b1-4a4af69e06fso6324795e9.2 for ; Fri, 06 Nov 2026 10:07:52 -0800 (PST) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=google.com; s=20260707; t=1793988471; x=1794593271; darn=vger.kernel.org; h=content-type:cc:to:from:subject:message-id:references:mime-version :in-reply-to:date:from:to:cc:subject:date:message-id:reply-to :content-type; bh=EuW+q0IZAiSlccInoGG1ZV09yqmS19RZQDDu5PkfcPQ=; b=UDP1eJ+KhmpIr7wybsu1glvXvBSx2mNVvyKwqSxdJ1pyt9ekZkC8gMJBNmSylo2G2S DOzPfIB/+eF5LtkZEtGDFLyM17Zmuc6kTFk4RfCvPy4hGH8kd4SMOYdhVvgjRhEiqMs8 knXo3ctfMDZEoe3BdQGK9P83EUaPVMqLdE/q84DYa9s/g6UT104ywYLkOBAOuiAiDj+o b3KrNM24i7d6F6eFyl3UjfNoL7s8zCPYxSOimlO3xjiPti3o2DpxD+O0MHuvHZUlU7TF wYD/HAH/NlgZvxhSaMmgwLVDkulTBwbq1VXxL3P1yUzCfvSBfwUm01c8qTywf05jAVZW 3zRw== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20260707; t=1793988471; x=1794593271; h=content-type:cc:to:from:subject:message-id:references:mime-version :in-reply-to:date:x-gm-message-state:from:to:cc:subject:date :message-id:reply-to:content-type; bh=EuW+q0IZAiSlccInoGG1ZV09yqmS19RZQDDu5PkfcPQ=; b=PuTbd/e+3TAfG1uz1kPnfveZ995UDmeTkghlVX322E0lsknyG4E2OlhF2GhHLp6GIp B0wr7uzwjrt9LlqeStzEy9GLBKjDwHPk3nN715cAn7VPeMIxxMjFvBXtn6OqZD1TClDI aKMEdB+vEUweR7CjwlyaDDhxZH5s1sck9nyqZ/GrZQwZ+Kyi2JTVMGW2g7C262QoU9Mi eOqaGsT+bhbktmKyly9C6KcDcjcfemmC5Tq7xxet7Ve9jCvtpx1rouXHqa1nJR5oLFzw Fzi+X2lvvlf9k/0nxtMIPtixwhCKbcj/f2dSKzBF5MUodQ0uuauU157LityTn4xr9ADa 2nDA== X-Forwarded-Encrypted: i=1; AKwUvByKoUN71WuKwqJxi2tFNMx4udpWGWq0cQwK3VJLs9Rd3Y1tCDmlWHJY9QQRHEK9sfM+Sw5d89yieas0jqvSGPpmmwk=@vger.kernel.org X-Gm-Message-State: APuU4Z/9u44huRa+XdKdvk//4nwxmvxy0+5P0CVuyo2Dtu1ckGPmYLtz Vx/heX5gfSDbaboHFwQWyH49lO+izE0rYzfRNYxTruO+btnFlN+d5+i8Btxy9WTCkRmg11euIOp mNv4lEllgE/mbFGO79Z3LoA== X-Received: from wmna17.prod.google.com ([2002:a05:600c:691:b0:4b2:3c81:ca]) (user=vdonnefort job=prod-delivery.src-stubby-dispatcher) by 2002:a05:600c:8b24:b0:49f:e701:51c8 with SMTP id 5b1f17b1804b1-4b6de4a766cmr59495905e9.9.1793988470935; Fri, 06 Nov 2026 10:07:50 -0800 (PST) Date: Fri, 6 Nov 2026 18:06:43 +0000 In-Reply-To: <20261106180657.2460376-1-vdonnefort@google.com> X-Mailing-List: linux-trace-kernel@vger.kernel.org List-Id: List-Post: List-Help: List-Subscribe: List-Unsubscribe: List-Owner: Precedence: list Mime-Version: 1.0 References: <20261106180657.2460376-1-vdonnefort@google.com> X-Mailer: git-send-email 2.56.0.455.g6c5a503b38-goog Message-ID: <20261106180657.2460376-8-vdonnefort@google.com> Subject: [PATCH v8 07/21] tracing/simple_ring_buffer: Add support for compressed length From: Vincent Donnefort To: rostedt@goodmis.org, mhiramat@kernel.org, linux-trace-kernel@vger.kernel.org Cc: mathieu.desnoyers@efficios.com, kernel-team@android.com, linux-kernel@vger.kernel.org, Vincent Donnefort Content-Type: text/plain; charset="UTF-8" The array length is the total size in bytes of the data for the current event. It is possible to compress this value into the event header type, which has 28 unused types, saving 32 bits for sufficiently small events. The compressed length is expressed as a multiple of the ring-buffer alignment, 4-bytes by default. Enforce this alignment. Signed-off-by: Vincent Donnefort --- kernel/trace/simple_ring_buffer.c | 23 ++++++++++++++++++----- 1 file changed, 18 insertions(+), 5 deletions(-) diff --git a/kernel/trace/simple_ring_buffer.c b/kernel/trace/simple_ring_buffer.c index abfaf9bee12e..a305331d29ba 100644 --- a/kernel/trace/simple_ring_buffer.c +++ b/kernel/trace/simple_ring_buffer.c @@ -207,7 +207,13 @@ static unsigned long rb_event_size(unsigned long length) { struct ring_buffer_event *event; - return length + RB_EVNT_HDR_SIZE + sizeof(event->array[0]); + if (!length) + length++; + + if (length > RB_MAX_SMALL_DATA || RB_FORCE_8BYTE_ALIGNMENT) + length += sizeof(event->array[0]); + + return ALIGN(length + RB_EVNT_HDR_SIZE, RB_ARCH_ALIGNMENT); } static struct ring_buffer_event * @@ -223,12 +229,15 @@ rb_event_add_ts_extend(struct ring_buffer_event *event, u64 delta) static struct ring_buffer_event * simple_rb_reserve_next(struct simple_rb_per_cpu *cpu_buffer, unsigned long length, u64 timestamp) { - unsigned long ts_ext_size = 0, event_size = rb_event_size(length); struct simple_buffer_page *tail = cpu_buffer->tail_page; + unsigned long event_size, array_size, ts_ext_size = 0; struct ring_buffer_event *event; u32 write, prev_write; u64 time_delta; + event_size = rb_event_size(length); + array_size = event_size - RB_EVNT_HDR_SIZE; + time_delta = timestamp - cpu_buffer->write_stamp; if (test_time_stamp(time_delta)) @@ -259,9 +268,13 @@ simple_rb_reserve_next(struct simple_rb_per_cpu *cpu_buffer, unsigned long lengt time_delta = 0; } - event->type_len = 0; + if (length > RB_MAX_SMALL_DATA || RB_FORCE_8BYTE_ALIGNMENT) { + event->type_len = 0; + event->array[0] = array_size; + } else { + event->type_len = DIV_ROUND_UP(array_size, RB_ALIGNMENT); + } event->time_delta = time_delta; - event->array[0] = event_size - RB_EVNT_HDR_SIZE; return event; } @@ -284,7 +297,7 @@ void *simple_ring_buffer_reserve(struct simple_rb_per_cpu *cpu_buffer, unsigned rb_event = simple_rb_reserve_next(cpu_buffer, length, timestamp); - return &rb_event->array[1]; + return rb_event->type_len ? &rb_event->array[0] : &rb_event->array[1]; } EXPORT_SYMBOL_GPL(simple_ring_buffer_reserve); -- 2.56.0.455.g6c5a503b38-goog