Re: [RFC] virtio-mem: paravirtualized memory

[Date Prev][Date Next][Thread Prev][Thread Next][Date Index][Thread Index]

 



On Fri, Jun 16, 2017 at 04:20:02PM +0200, David Hildenbrand wrote:
> Important restrictions of this concept:
> - Guests without a virtio-mem guest driver can't see that memory.
> - We will always require some boot memory that cannot get unplugged.
>   Also, virtio-mem memory (as all other hotplugged memory) cannot become
>   DMA memory under Linux. So the boot memory also defines the amount of
>   DMA memory.

I didn't know that hotplug memory cannot become DMA memory.

Ouch.  Zero-copy disk I/O with O_DIRECT and network I/O with virtio-net
won't be possible.

When running an application that uses O_DIRECT file I/O this probably
means we now have 2 copies of pages in memory: 1. in the application and
2. in the kernel page cache.

So this increases pressure on the page cache and reduces performance :(.

Stefan

Attachment: signature.asc
Description: PGP signature


[Index of Archives]     [Linux ARM Kernel]     [Linux ARM]     [Linux Omap]     [Fedora ARM]     [IETF Annouce]     [Bugtraq]     [Linux OMAP]     [Linux MIPS]     [eCos]     [Asterisk Internet PBX]     [Linux API]
  Powered by Linux