Re: [PATCH v8 1/4] libs/call: cache up to 4 pages in hypercall bounce buffers

[Anthony PERARD <anthony.perard@xxxxxxxxxx>]

On Sat, Jul 11, 2026 at 10:21:25PM +0100, Frediano Ziglio wrote:
> From: Edwin Török <edwin.torok@xxxxxxxxxx>
> 
> During migration there are a lot of mmap/munmap calls,
> because xc_get_pfn_type_batch() exceeds the default hypercall bounce
> buffer cache size, and needs to allocate every time it is called.
> 
> munmap() is slow, especially in a PV Dom0 (takes an emulation fault),
> so is best avoided.
> 
> Eventually it'd be good if the memory pool from  xmalloc_tlsf.c
> was reused here, but for now make it handle the commonly encountered
> sizes (so far up to 4 pages).
> 
> Signed-off-by: Edwin Török <edwin.torok@xxxxxxxxxx>
> Signed-off-by: Frediano Ziglio <frediano.ziglio@xxxxxxxxxx>

Reviewed-by: Anthony PERARD <anthony.perard@xxxxxxxxxx>

Thanks,


--
Anthony Perard | Vates XCP-ng Developer

XCP-ng & Xen Orchestra - Vates solutions

web: https://vates.tech