From mboxrd@z Thu Jan 1 00:00:00 1970 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 A88462877C1; Thu, 10 Jul 2025 10:59:18 +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=1752145159; cv=none; b=fw1+2bDs/LxQBZtFOIN/Le7CrHyLE13ceG2MmvOudr+tW8CLfTc6VMcNlFikyLj9BztG9k4w/XvKVw/uOnSPifUOuOt2kZgcm98rSxYbihWJzrghmoJxS96sqvIGgoxC/w8tDmIp4iZVYRfuF4mm5wICmr2yPmoUScs0Zv3bJxg= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1752145159; c=relaxed/simple; bh=+9Aiaj5Zj4iemiwWv8ITBr4HJpVztCAHhr9QST4AMpM=; h=Date:From:To:Cc:Subject:Message-ID:In-Reply-To:References: MIME-Version:Content-Type; b=szbwSuLfYociy5OcU6D1UwPELm0y3BVO8y4j95jjH1t8yWEkFreTXNRKbuICIOHNOeTnvOjscPu6zyCAs/x65Bfi9MIg97go1tdpDiAf7DXqT2ryxG+m53yxrHGAUfO+BMRczHoqvJNcKI53yaO2LwfHOlkT7oZkbYTWV6BmF+Y= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b=mYNHFa70; arc=none smtp.client-ip=10.30.226.201 Authentication-Results: smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b="mYNHFa70" Received: by smtp.kernel.org (Postfix) with ESMTPSA id 18449C4CEE3; Thu, 10 Jul 2025 10:59:16 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=k20201202; t=1752145158; bh=+9Aiaj5Zj4iemiwWv8ITBr4HJpVztCAHhr9QST4AMpM=; h=Date:From:To:Cc:Subject:In-Reply-To:References:From; b=mYNHFa70nvJ50iL0uCKjVAMeHVhRxcAByGoCreYB1OOp3FDxAgj18gj/ArF19YSCY rfC9xCmDPyFvE3H32en0cVmTRA1Tpzgzr01k8K2bXxpv8UB3gecqtB6h0zYx/Lesuz ws9IQkzBfoBYuHsps28B4NHdktVFPwACRAF47jULOSaWQ+l/5qfAdlZU++HuUQFfvO Y45AY4AoH32nhwtXeA2aWKohzAcZhOQPEPXu4LEJCwm51H5PRfjr2m77WIUSsxVKk8 /USo0wB7j1g532G0k17lWxSr6djiN3MtrSURwsnbONHi/NS4f58v80xNMAWYxM2Yom uI/X1Rgqq5gsw== Date: Thu, 10 Jul 2025 12:59:14 +0200 From: Mauro Carvalho Chehab To: Jonathan Corbet Cc: linux-doc@vger.kernel.org, linux-kernel@vger.kernel.org, Akira Yokosawa Subject: Re: [PATCH 12/12] docs: kdoc: Improve the output text accumulation Message-ID: <20250710125914.41fe8cf6@foz.lan> In-Reply-To: <20250710123155.1045831d@foz.lan> References: <20250702223524.231794-1-corbet@lwn.net> <20250702223524.231794-13-corbet@lwn.net> <20250710084119.3e5c1ced@foz.lan> <20250710091352.4ae01211@foz.lan> <20250710101931.202953d1@foz.lan> <20250710121033.42db5ef3@foz.lan> <20250710123155.1045831d@foz.lan> X-Mailer: Claws Mail 4.3.1 (GTK 3.24.49; x86_64-redhat-linux-gnu) Precedence: bulk X-Mailing-List: linux-doc@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Type: text/plain; charset=US-ASCII Content-Transfer-Encoding: 7bit Em Thu, 10 Jul 2025 12:31:55 +0200 Mauro Carvalho Chehab escreveu: > Em Thu, 10 Jul 2025 12:10:33 +0200 > Mauro Carvalho Chehab escreveu: > > > From the above: > > > > - It is not worth applying patch 12/12 as it makes the code slower; > > - Python 3.13t (no-GIL version) had very bad results. It seems it > > still requires optimization; > > - Python 3.9 is a lot worse (140% to 190%) when using list append; > > - when there are not many concats, Python 3.13 is about 15% slower > > with lists than concat strings. It only approaches str concat > > when the number of concats is high. > > > > With the above, clearly str += is faster than list append. > > > > So, except if I did something wrong on this benchmark script, please > > don't apply patch 12/12. > > And I did: I forgot the final line at the concat code to get the > result as strings. > > For explicit list: > result = obj.output() > > For implicit ones: > result = str(obj) > > Yet, the conclusion is similar. With Python 3.13: > > $ for i in python3.13; do for j in 1 10 100 1000; do $i /tmp/bench.py $((1000000/$j)) $j 1; done; done > 1 strings in a loop with 1000000 interactions, repeating 24 times > str += : time: 41.42 > list join : time: 127.33: 207.42% slower than str += > 10 strings in a loop with 100000 interactions, repeating 24 times > str += : time: 27.15 > list join : time: 39.19: 44.36% slower than str += > 100 strings in a loop with 10000 interactions, repeating 24 times > str += : time: 24.84 > list join : time: 30.70: 23.57% slower than str += > 1000 strings in a loop with 1000 interactions, repeating 24 times > str += : time: 21.84 > list join : time: 27.85: 27.50% slower than str += > > Explict list concat was between ~30% to ~200% worse than str concat. Looking for an explanation, PEP 509 and PEP 393 did Short String Optimization and Inline Caching. This was applied Python 3.6, and Python 3.13 came with extra string optimizations. On the other hand, lists do more memory allocations, have some logic to extend list growth and has an extra concat loop. With that, contrary to popular belief, it sounds that str concat are nowadays faster. Thanks, Mauro