linux-kernel - Re: [PATCH 1/3] i915/gvt: seperate tracked MMIO table from handlers.c

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Message-ID: <040f15a2-e538-8762-1a85-82df0c4190cc@intel.com>
Date:   Tue, 9 Nov 2021 11:02:28 +0000
From:   "Wang, Zhi A" <zhi.a.wang@...el.com>
To:     "hch@....de" <hch@....de>
CC:     Jani Nikula <jani.nikula@...ux.intel.com>,
        Zhi Wang <zhi.wang.linux@...il.com>,
        "joonas.lahtinen@...ux.intel.com" <joonas.lahtinen@...ux.intel.com>,
        "Vivi, Rodrigo" <rodrigo.vivi@...el.com>,
        "zhenyuw@...ux.intel.com" <zhenyuw@...ux.intel.com>,
        "jgg@...dia.com" <jgg@...dia.com>,
        "intel-gfx@...ts.freedesktop.org" <intel-gfx@...ts.freedesktop.org>,
        "intel-gvt-dev@...ts.freedesktop.org" 
        <intel-gvt-dev@...ts.freedesktop.org>,
        "dri-devel@...ts.freedesktop.org" <dri-devel@...ts.freedesktop.org>,
        "linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>
Subject: Re: [PATCH 1/3] i915/gvt: seperate tracked MMIO table from handlers.c

On 11/9/2021 12:58 PM, hch@....de wrote:
> On Tue, Nov 09, 2021 at 10:51:27AM +0000, Wang, Zhi A wrote:
>> Can you elaborate more about this? We need the hash query from the table
>> ASAP when the hypervisor trapped a mmio access. It's a critical path and
>> we tried different data structure in the kernel and the hash table gives
>> the best performance.
> Ok, I misunderstood the hashtable.h interface.  hash_for_each_possible
> actually does a hash lookup instead of an interation despite the rather
> misleading name.

Yes. Maybe with a keyword "lookup" in the name of the interface would be 
better since it's widely used in the kernel. :)