From: Neil Brown <neilb@suse.de>
Subject: Re: [PATCH 5/8] knfsd: repcache: dynamically expand under load
Date: Mon, 16 Oct 2006 20:15:52 +1000
Message-ID: <17715.23512.3204.567488@cse.unsw.edu.au>
References: <1160566088.8530.15.camel@hole.melbourne.sgi.com>
	<17714.60137.447459.323573@cse.unsw.edu.au>
	<20061016100540.GC8568@sgi.com>
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Cc: Linux NFS Mailing List <nfs@lists.sourceforge.net>
To: Greg Banks <gnb@sgi.com>
In-Reply-To: message from Greg Banks on Monday October 16
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On Monday October 16, gnb@sgi.com wrote:
> 
> How about this?
> 
>  	b->nhits++;
>  	if (b->last == 0) {
>  		b->last = now;
>  	} else if (time_after(now, b->last + CACHE_MAX_WAIT)) {
>  		b->last = now; /* too slow */
>  		b->nhits >>= 1;
>  		return 0;
>  	} else if (time_after(now, b->last + CACHE_RATE_JIFFIES) &&
>  		   b->nhits > (b->size >> 4)) {
>  		b->nhits = 0;
>  		b->last = now;
>  		return 1;
>  	}
>  	return 0;
>  
> It gives a damping factor without totally forgetting the past hits.
> Otherwise the case of a regular burst every 61 seconds fails to expand
> the repcache, which I think it should.

Works for me.  Definite improvement.

Thanks,
NeilBrown

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