Re: [Libguestfs] libnbd flamegraph Odd benchmark results

On Sat, May 29, 2021 at 09:46:08PM +0100, Richard W.M. Jones wrote: To be clearer, I mean that if we allocate (default) 32MB buffers and have (default) 64 requests in flight and have (default) 4 connections open, then in theory there could be 32 * 64 * 4 MB of memory being used at once. That is 8 GB -- although in reality it would probably not be that much. Also each single buffer is larger than my test machine's L3 cache. Then there's the problem that Nir also pointed out that we don't reuse these memory buffers, so we depend on whatever malloc() does, and may or may not be reusing the memory in a cache-efficient way. Rich. -- Richard Jones, Virtualization Group, Red Hat http://people.redhat.com/~rjones Read my programming and virtualization blog: http://rwmj.wordpress.com virt-builder quickly builds VMs from scratch http://libguestfs.org/virt-builder.1.html