Date: Mon, 03 Nov 2014 09:29:06 +0100 From: Hans Petter Selasky <hps@selasky.org> To: Julian Elischer <julian@freebsd.org>, Mateusz Guzik <mjg@FreeBSD.org>, src-committers@freebsd.org, svn-src-all@freebsd.org, svn-src-head@freebsd.org Subject: Re: svn commit: r274017 - head/sys/kern Message-ID: <54573CD2.1000702@selasky.org> In-Reply-To: <54573B87.7000801@freebsd.org> References: <201411030746.sA37kpPu037113@svn.freebsd.org> <54573AEE.9010602@freebsd.org> <54573B87.7000801@freebsd.org>
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On 11/03/14 09:23, Julian Elischer wrote: > On 11/3/14, 4:21 PM, Julian Elischer wrote: >> On 11/3/14, 3:46 PM, Mateusz Guzik wrote: >>> Author: mjg >>> Date: Mon Nov 3 07:46:51 2014 >>> New Revision: 274017 >>> URL: https://svnweb.freebsd.org/changeset/base/274017 >>> >>> Log: >>> Provide an on-stack temporary buffer for small ioctl requests. >> I'm not sure I like this. We don't know how many more levels >> of stack may be needed. >> I know that machines are getting faster with more memory, >> but the current move towards bloating out the > ... "bloating out the stack" ... >> worries me. we started out with a single page of stack (SHARED >> with the U-area!). I think we are now at several pages.. I forget, is >> it 8? >> I'm open to being persuaded but I think we need to have a discussion >> about stack usage. We used to say that anything greater that, say >> 64 bytes should probably be allocated. >> Hi, I think this patch can give a benefit for the USB stack and CUSE4BSD, because it does frequent IOCTLs. Regarding the stack usage, maybe this general purpose optimisation can be allocated from the thread structure? --HPS
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