Re: [PATCH 1/3] hw/virtio: Optimize vhost_log_sync_range to avoid N^2 complexity

Xiong Weimin <[email protected]> Fri, 7 Aug 2026 10:43:50 +0800
Newsgroups dev.linux.lists.virtualization,org.nongnu.qemu-devel
Message-ID <[email protected]>
On Fri, Jul 24, 2026 at 05:56:03AM -0400, Michael S. Tsirkin wrote:
> As any optimization, I expect actual perf measurements
> showing an improvement to be included please.
>
> So it is still O(N^2) right? It just skips calling it for
> some sections.

You are right.  The change only skipped non-overlapping sections and
did not really address the complexity, and I do not have measurements
showing a meaningful win on the only call site (full-range sync in
vhost_log_put).

I will drop this patch.

Thanks,
Xiong Weimin