Date: Thu, 21 May 2009 23:23:11 +0200 From: Nathan Whitehorn <nwhitehorn@freebsd.org> To: Marcel Moolenaar <xcllnt@mac.com> Cc: Peter Grehan <grehan@freebsd.org>, FreeBSD PowerPC ML <freebsd-ppc@freebsd.org> Subject: Re: [patch] __syncicache: eliminate D-cache flush Message-ID: <4A15C63F.60505@freebsd.org> In-Reply-To: <15E5E194-708A-4FA6-B105-2A85EE8B6982@mac.com> References: <20090522032558.ETR51534@dommail.onthenet.com.au> <15E5E194-708A-4FA6-B105-2A85EE8B6982@mac.com>
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Marcel Moolenaar wrote: > > On May 21, 2009, at 10:25 AM, Peter Grehan wrote: > >> Hi Marcel, >> >>> I'd like to commit the following change, which basically >>> removes the D-cache flush from syncicache. >> >> Isn't that required so that future instruction fetches will >> always pull in the value from memory and not have it sitting >> in the d-cache waiting to be flushed ? > > We make sure that D-caches are flushed elsewhere. On the > one hand we have DMA-based I/O, for which the platform > guarantees coherency (if not, then busdma(9) fills the gap). > On the other hand we have md(4), NFS, etc, which use bcopy(9). > For those I recently added cpu_flush_dcache() so that they > flush the D-cache explicitly (needed because you sometimes > need to flush the D-cache based on the VA used for the copy) > At this time cpu_flush_dcache() is not implemented for AIM > nor booke. So far it doesn't look like it's needed on my > Xserve G4, but the email was to make sure that I have the > full picture. We may need to implement cpu_flush_dcache() > for G3 or G5 processors... I'm currently out of town (working in Germany at DESY Zeuthen), and won't be able to test this on G5s before the 8.0 feature freeze. Does anyone else have a G5 system where this can be tested? -Nathan
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