Date: Wed, 10 Oct 2007 11:12:59 -0700 From: David G Lawrence <dg@dglawrence.com> To: Igor Sysoev <is@rambler-co.ru> Cc: Kostik Belousov <kostikbel@gmail.com>, freebsd-current@freebsd.org, Antony Mawer <fbsd-current@mawer.org> Subject: Re: sendfile and page usage statistics Message-ID: <20071010181259.GF56714@tnn.dglawrence.com> In-Reply-To: <20071010173601.GB35652@rambler-co.ru> References: <20071009125001.GC5758@rambler-co.ru> <20071010055748.GA18931@rambler-co.ru> <20071010060605.GB18931@rambler-co.ru> <470C6DD4.1060509@mawer.org> <20071010062541.GA23840@rambler-co.ru> <20071010093436.GB2180@deviant.kiev.zoral.com.ua> <20071010095018.GA28123@rambler-co.ru> <20071010102756.GE56714@tnn.dglawrence.com> <20071010173601.GB35652@rambler-co.ru>
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> The read() from file certainly updates vnode pages' PG_A/PG_REFERENCED, > because coping to userland is made by CPU. I think write() does the same. No, it does not. The kernel virtual mappings involved in that copy are "special"; page bits (PG_A, PG_M, etc) from those mapping are not preserved from the PTEs (at least not on x86). -DG David G. Lawrence President Download Technologies, Inc. - http://www.downloadtech.com - (866) 399 8500 The FreeBSD Project - http://www.freebsd.org Pave the road of life with opportunities.
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