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Date:   Wed, 19 Sep 2018 00:23:51 +0300
From:   Leon Romanovsky <leon@kernel.org>
To:     Jason Gunthorpe <jgg@ziepe.ca>
Cc:     Jan Dakinevich <jan.dakinevich@virtuozzo.com>,
        Doug Ledford <dledford@redhat.com>,
        Yishai Hadas <yishaih@mellanox.com>,
        Parav Pandit <parav@mellanox.com>,
        Mark Bloch <markb@mellanox.com>,
        Daniel Jurgens <danielj@mellanox.com>,
        Kees Cook <keescook@chromium.org>,
        Kamal Heib <kamalheib1@gmail.com>,
        Bart Van Assche <bvanassche@acm.org>,
        linux-rdma@vger.kernel.org, linux-kernel@vger.kernel.org,
        Denis Lunev <den@virtuozzo.com>,
        Konstantin Khorenko <khorenko@virtuozzo.com>
Subject: Re: [PATCH 0/4] IB: decrease large contigous allocation
Message-ID: <20180918212351.GB3661@mtr-leonro.mtl.com>
References: <1537275826-27247-1-git-send-email-jan.dakinevich@virtuozzo.com>
 <20180918144623.GI11367@ziepe.ca>
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On Tue, Sep 18, 2018 at 08:46:23AM -0600, Jason Gunthorpe wrote:
> On Tue, Sep 18, 2018 at 04:03:42PM +0300, Jan Dakinevich wrote:
> > The size of mlx4_ib_device became too large to be allocated as whole contigous
> > block of memory. Currently it takes about 55K. On architecture with 4K page it
> > means 3rd order.
> >
> > This patch series makes an attempt to split mlx4_ib_device into several parts
> > and allocate them with less expensive kvzalloc
>
> Why split it up? Any reason not to just allocate the whole thing with
> kvzalloc?

And before we are rushing to dissect mlx4_ib driver, can you
explain the rationale behind this change? The mlx4_ib driver
represents high-performance device which needs enough memory
resources to operate. Those devices are limited by number
of PCIs and SRIOV VFs (upto 126) and very rare allocated/deallocated.

I would like to see real rationale behind such change.

Thanks

>
> Jason

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