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Re: Performance bug in c-r4k.c cache handling code

To: Atsushi Nemoto <>
Subject: Re: Performance bug in c-r4k.c cache handling code
From: Thiemo Seufer <>
Date: Mon, 19 Sep 2005 20:31:18 +0200
In-reply-to: <>
Original-recipient: rfc822;
References: <20050919154056.GG3386@hattusa.textio> <>
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Atsushi Nemoto wrote:
> >>>>> On Mon, 19 Sep 2005 17:40:56 +0200, Thiemo Seufer <> 
> >>>>> said:
> ths> I found an performance bug in c-r4k.c:r4k_dma_cache_inv, where a
> ths> Hit_Writeback_Inv instead of Hit_Invalidate is done. Ralf
> ths> mentioned this is probably due to broken Hit_Invalidate cache ops
> ths> on some CPUs, does anybody have more information about this? The
> ths> appended patch works apparently fine on R4400, R4600v2.0, R5000.
> Just a question: Are there any performance advantage of using
> Hit_Invalidate instead of Hit_Writeback_Inv if the target line was

I wouldn't think so, but it depends on the particular implementation.


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