On Mon, Feb 14, 2022 at 04:08:21PM +0000, Richard W.M. Jones wrote: > There is a limit on the number of parallel requests in flight > (nbdcopy --requests, default 64). This limits the implicit buffer to > max_requests * request_size. That's 16MB in the default > configuration. Quite small actually ... > > https://gitlab.com/nbdkit/libnbd/-/blob/6725fa0e129f9a60d7b89707ef8604e0aeeeaf43/copy/multi-thread-copying.c#L239 > > I've managed to reproduce the problem locally now so I can try playing > with this limit.
Or rather, I thought I'd reproduced it, but after repeating the test a few times it's just ordinary variability. Anyhow I tried increasing the nbdcopy --requests parameter to 64->256 but it didn't change the speed (faster or slower). Rich. -- Richard Jones, Virtualization Group, Red Hat http://people.redhat.com/~rjones Read my programming and virtualization blog: http://rwmj.wordpress.com Fedora Windows cross-compiler. Compile Windows programs, test, and build Windows installers. Over 100 libraries supported. http://fedoraproject.org/wiki/MinGW _______________________________________________ Libguestfs mailing list Libguestfs@redhat.com https://listman.redhat.com/mailman/listinfo/libguestfs