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From: "Roger Pau Monné" <roger.pau@citrix.com>
To: Stefano Stabellini <sstabellini@kernel.org>
Cc: Oleksandr <olekstysh@gmail.com>,
	xen-devel@lists.xenproject.org, linux-kernel@vger.kernel.org,
	Oleksandr Tyshchenko <oleksandr_tyshchenko@epam.com>,
	Boris Ostrovsky <boris.ostrovsky@oracle.com>,
	Juergen Gross <jgross@suse.com>, Julien Grall <julien@xen.org>
Subject: Re: [RFC PATCH 1/2] xen/unpopulated-alloc: Introduce helpers for DMA allocations
Date: Thu, 16 Jun 2022 10:49:34 +0200	[thread overview]
Message-ID: <YqrunrtBjWPgdlDi@Air-de-Roger> (raw)
In-Reply-To: <alpine.DEB.2.22.394.2206141735430.1837490@ubuntu-linux-20-04-desktop>

On Tue, Jun 14, 2022 at 05:45:53PM -0700, Stefano Stabellini wrote:
> Basically, if we allocate (and free) page-by-page it leads to more
> efficient resource utilization but it is slower. If we allocate larger
> contiguous chunks it is faster but it leads to less efficient resource
> utilization.
> 
> Given that on both x86 and ARM the unpopulated memory resource is
> arbitrarily large, I don't think we need to worry about resource
> utilization. It is not backed by real memory. The only limitation is the
> address space size which is very large.

Well, unpopulated memory will consume memory to populate the related
metadata (ie: struct page and realted tracking information) for the
unpopulated region, so it's not completely free.

Thanks, Roger.


  parent reply	other threads:[~2022-06-16  8:50 UTC|newest]

Thread overview: 16+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2022-05-17 18:04 [RFC PATCH 0/2] Ability to allocate DMAable pages using unpopulated-alloc Oleksandr Tyshchenko
2022-05-17 18:04 ` [RFC PATCH 1/2] xen/unpopulated-alloc: Introduce helpers for DMA allocations Oleksandr Tyshchenko
2022-06-03 21:52   ` Stefano Stabellini
2022-06-08 18:12     ` Oleksandr
2022-06-11  0:12       ` Stefano Stabellini
2022-06-14 17:37         ` Oleksandr
2022-06-15  0:45           ` Stefano Stabellini
2022-06-15 16:56             ` Oleksandr
2022-06-16  8:49             ` Roger Pau Monné [this message]
2022-05-17 18:04 ` [RFC PATCH 2/2] xen/grant-table: Use unpopulated DMAable pages instead of real RAM ones Oleksandr Tyshchenko
2022-06-03 21:19   ` Stefano Stabellini
2022-06-09 18:39     ` Oleksandr
2022-06-10 23:55       ` Stefano Stabellini
2022-06-14 17:53         ` Oleksandr
2022-06-15  0:51           ` Stefano Stabellini
2022-06-15 16:40             ` Oleksandr

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