From mboxrd@z Thu Jan 1 00:00:00 1970 From: Dirk Behme Subject: Re: Boot time: Kernel start parallelization issue? Date: Sat, 15 Jan 2011 17:18:13 +0100 Message-ID: <4D31C8C5.6010306@googlemail.com> References: <4D315D86.40401@googlemail.com> <4D31C034.8040105@linux.intel.com> Mime-Version: 1.0 Content-Transfer-Encoding: 7bit Return-path: DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=googlemail.com; s=gamma; h=domainkey-signature:message-id:date:from:user-agent:mime-version:to :cc:subject:references:in-reply-to:content-type :content-transfer-encoding; bh=7sAau1V8Xdag0FqNqr29SIRBtLwgWqIxs5GSwtT3i3o=; b=o0A5fhL5xepPeeB12IeB9MLmLygmGiffDII5fUxJ0RigG90DDU037+oxTX6g/oL26h C1mBx2pUJiays1eZlBnfAEGBcmF+W3f7JIwRwMXbMPwZQgUMg6KR7ydWlrUSgHmxlrmu Un9ejQadYa4g1PLRuaVbj1ijemGjSawg3gYlU= In-Reply-To: <4D31C034.8040105@linux.intel.com> Sender: linux-embedded-owner@vger.kernel.org List-ID: Content-Type: text/plain; charset="us-ascii"; format="flowed" To: Arjan van de Ven Cc: linux-embedded@vger.kernel.org, Greg KH , Martin Mueller On 15.01.2011 16:41, Arjan van de Ven wrote: > On 1/15/2011 12:40 AM, Dirk Behme wrote: >> >> There are some reports [1] [2] looking at the boot time of embedded >> (ARM?) systems using initcall debug [3]. Both reports seem to show >> that they have issues with the start up sequence of the kernel being >> completely single-threaded. In [2] Greg mentions that on a x86 box >> multi-threads are happening and that there he doesn't see this >> issue. On the other hand, both reports mention Arjan's async >> initcall patches [4] to help against the issue. I.e. introducing >> some parallelization (on ARM) does help, too. >> >> With this, I wonder >> >> - if anybody faces similar issues with single-threaded only kernel >> start on embedded (ARM?) systems? Or if this is known? Or if there >> are fixes for this? >> >> - if we somehow should try to 're-activate' Arjan's async initcall >> patches? > > those patches are obsoleted by the merged async_schedule() calls. Any link (patch name, git link) to be able to check for async_schedule() calls? > what kernel are you seeing issues on? [1] talks about 2.6.28, [2] talks about 2.6.34. Best regards Dirk [1] http://www.lindusembedded.com/blog/2010/06/02/measuring-the-boot-time-of-an-embedded-linux-device/ [2] http://thread.gmane.org/gmane.linux.usb.general/41181 (mainly the last mail of this thread: http://article.gmane.org/gmane.linux.usb.general/41619)