Re: [Xen-ia64-devel] [PATCH] work around for populate physmap hypercall

[Alex Williamson <alex.williamson@xxxxxx>]

On Mon, 2007-08-20 at 12:23 +0900, Isaku Yamahata wrote:
> Hi.
> This patch is work around for xencomm and the soft lockup message.
> However I need help before commit.
> 
> - It is necessary to test it before commit with much memory.
>   I haven't tested it with much memory because my environment doesn't have
>   such huge memory.
> - I defined MEMORYOP_MAX_EXTENTS based on the xencomm limitation.
>   Howver I'm not sure the value is small enough to avoid the soft lockup
>   message because I couldn't produce the message on my environment.
>   It is necessary to determine the value with expriments.

Hi Isaku,

   The defined MEMORYOP_MAX_EXTENTS is still a bit too big, I get soft
lockups with large domains.  Further testing shows dividing your
MEMORYOP_MAX_EXTENTS calculation by 4 gives me nearly 1 million extents,
and eliminates the soft lockup.  I've tested up to a 90G domain with no
problems on startup.  Here's the macro I end up with:

#define MEMORYOP_MAX_EXTENTS                                            \
                ((((((PAGE_SIZE - sizeof(struct xencomm_desc)) /        \
                   sizeof(uint64_t)) - 2) * PAGE_SIZE) /                \
                  sizeof(*xen_guest_handle(kern_op.extent_start))) / 4)

Thanks,

        Alex

-- 
Alex Williamson                             HP Open Source & Linux Org.


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