Hello, Although it's useful to mount random media more safely than it would be using kernel-space, I noticed that using 64KB reads, the kernel cd9660 will gladly read ~20MB/s from a DVD, but that rump_cd9660 using 64KB reads is limited to aproximately 4MB/s at most, even if the system is mostly idle during those transfers (on netbsd-6/amd64 and 4 3.3GHz cores).
This also reminds me of pty related issues with the previously small buffer size, and whenever the buffer could be made larger, throughput was much better. However, this is already using a 64KB buffer, which seems fairly large. I didn't investigate it but I suspect that frequent context switches might be the problem, or perhaps some rump HZ or virtual-interrupts frequency issue. It's not a critical problem (I can simply use the pure kernel FS implementation, and I understand that Rump is still useful for testing/debugging), but I wondered if anyone already knew exactly what limits the troughput, and if there's an easy fix... Probably that an alternative might be to try a Puffs/FUSE ISO-9660 implementation, but I didn't find such under pkgsrc/filesystems/ (and from previous experience porting FUSE filesystems is sometimes non-trivial). I haven't tested recently, but I think that I remember rump_msdos also being slow on USB flash devices compared to using mount_msdos. Thanks, -- Matt
