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=-1.1 required=3.0 tests=DKIMWL_WL_HIGH,DKIM_SIGNED, DKIM_VALID,DKIM_VALID_AU,MAILING_LIST_MULTI,SPF_HELO_NONE,SPF_PASS autolearn=no 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 E6E77C7618F for ; Mon, 15 Jul 2019 22:04:11 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id BE37E2173C for ; Mon, 15 Jul 2019 22:04:11 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=default; t=1563228251; bh=lzmzGxC84ycn5YPcgrlTTZCsaQHNzr70lnAMErLcD6E=; h=In-Reply-To:References:From:To:Subject:Cc:Date:List-ID:From; b=hCYq7lxCroq/yVioSRE7XWxxcUDOG9/qX2rkeuZSMJvhfsyX516aUsecl59DGmeFm V3nzC36yjkmm24W1kiFxylpPE/GoE+0ILBqF4mHVb7MtoOBcU1XdUXq9wd6X54v5Ro IFTiTft0a8VfXodAXvrb30JmTcuOkP4dfuWwr6f4= Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1732229AbfGOWEI (ORCPT ); Mon, 15 Jul 2019 18:04:08 -0400 Received: from mail.kernel.org ([198.145.29.99]:33906 "EHLO mail.kernel.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1730647AbfGOWEI (ORCPT ); Mon, 15 Jul 2019 18:04:08 -0400 Received: from kernel.org (unknown [104.132.0.74]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by mail.kernel.org (Postfix) with ESMTPSA id 0030420665; Mon, 15 Jul 2019 22:04:06 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=default; t=1563228247; bh=lzmzGxC84ycn5YPcgrlTTZCsaQHNzr70lnAMErLcD6E=; h=In-Reply-To:References:From:To:Subject:Cc:Date:From; b=yjILvyTeOyRdWTjel54BWNGgZ1ntKYib3gQKxCNMZGijJY1OIFiN5Q/Cq5W/Sq65r OjyZGX9OeeT3oFA8a4sDcYrXowZlMFMynYaGOGbEAJsQkEWD3FqBmHRAOOmQwn1vSW sbrWnUD7cVteQcJnCcGYDIxrhTqiEX8IEogTyyrs= Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: quoted-printable In-Reply-To: References: <20190712081744.87097-1-brendanhiggins@google.com> <20190712081744.87097-4-brendanhiggins@google.com> <20190715204356.4E3F92145D@mail.kernel.org> From: Stephen Boyd To: Brendan Higgins Subject: Re: [PATCH v9 03/18] kunit: test: add string_stream a std::stream like string builder Cc: Frank Rowand , Greg KH , Josh Poimboeuf , Kees Cook , Kieran Bingham , Luis Chamberlain , Peter Zijlstra , Rob Herring , shuah , Theodore Ts'o , Masahiro Yamada , devicetree , dri-devel , kunit-dev@googlegroups.com, "open list:DOCUMENTATION" , linux-fsdevel@vger.kernel.org, linux-kbuild , Linux Kernel Mailing List , "open list:KERNEL SELFTEST FRAMEWORK" , linux-nvdimm , linux-um@lists.infradead.org, Sasha Levin , "Bird, Timothy" , Amir Goldstein , Dan Carpenter , Daniel Vetter , Jeff Dike , Joel Stanley , Julia Lawall , Kevin Hilman , Knut Omang , Logan Gunthorpe , Michael Ellerman , Petr Mladek , Randy Dunlap , Richard Weinberger , David Rientjes , Steven Rostedt , wfg@linux.intel.com User-Agent: alot/0.8.1 Date: Mon, 15 Jul 2019 15:04:06 -0700 Message-Id: <20190715220407.0030420665@mail.kernel.org> Sender: linux-kselftest-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kselftest@vger.kernel.org Quoting Brendan Higgins (2019-07-15 14:11:50) > On Mon, Jul 15, 2019 at 1:43 PM Stephen Boyd wrote: > > > > I also wonder if it would be better to just have a big slop buffer of a > > 4K page or something so that we almost never have to allocate anything > > with a string_stream and we can just rely on a reader consuming data > > while writers are writing. That might work out better, but I don't quite > > understand the use case for the string stream. >=20 > That makes sense, but might that also waste memory since we will > almost never need that much memory? Why do we care? These are unit tests. Having allocations in here makes things more complicated, whereas it would be simpler to have a pointer and a spinlock operating on a chunk of memory that gets flushed out periodically.