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From:   Nathan Lynch <nathanl@linux.ibm.com>
To:     Scott Cheloha <cheloha@linux.ibm.com>
Cc:     Nathan Fontenont <ndfont@gmail.com>,
        Rick Lindsley <ricklind@linux.vnet.ibm.com>,
        linuxppc-dev@lists.ozlabs.org, linux-kernel@vger.kernel.org,
        Michael Ellerman <mpe@ellerman.id.au>
Subject: Re: [PATCH] powerpc/drmem: cache LMBs in xarray to accelerate lookup
In-Reply-To: <20200128221113.17158-1-cheloha@linux.ibm.com>
References: <20200128221113.17158-1-cheloha@linux.ibm.com>
Date:   Tue, 28 Jan 2020 17:56:55 -0600
Message-ID: <87pnf3i188.fsf@linux.ibm.com>
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Scott Cheloha <cheloha@linux.ibm.com> writes:
> LMB lookup is currently an O(n) linear search.  This scales poorly when
> there are many LMBs.
>
> If we cache each LMB by both its base address and its DRC index
> in an xarray we can cut lookups to O(log n), greatly accelerating
> drmem initialization and memory hotplug.
>
> This patch introduces two xarrays of of LMBs and fills them during
> drmem initialization.  The patch also adds two interfaces for LMB
> lookup.

Good but can you replace the array of LMBs altogether
(drmem_info->lmbs)? xarray allows iteration over the members if needed.