Date: Fri, 14 Nov 2014 15:41:36 +0100
From: Radim =?utf-8?B?S3LEjW3DocWZ?= <rkrcmar@redhat.com>
To: Igor Mammedov <imammedo@redhat.com>
Cc: Paolo Bonzini <pbonzini@redhat.com>, linux-kernel@vger.kernel.org,
        kvm@vger.kernel.org, yoshikawa_takuya_b1@lab.ntt.co.jp
Subject: Re: [PATCH 1/3] kvm: memslots: track id_to_index changes during the
 insertion sort
Message-ID: <20141114144135.GC27697@potion.brq.redhat.com>
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 <20141114133500.GA10593@potion.brq.redhat.com>
 <20141114151725.55774165@igors-macbook-pro.local>
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2014-11-14 15:17+0100, Igor Mammedov:
> > (We'll have to change it into an interval tree, or something, if the
> >  number of slots rises anyway.)
> Only if it rises to huge amount, I've played with proposed 512 memslots
> and it takes ~10000 cycles which is 5% of current heapsort overhead.
> Taking in account that it's slow path anyway, it's unlikely that there
> would be need to speedup this case even more.

Yes, your improvement is great and would work even for higher amounts.

I meant that our lookup is currently pretty sad -- O(N) that is
presumably optimized by looking at the largest regions first.

Maybe we would benefit from O(log N) lookup even with 128 memslots.
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