[syslinux] memdisk speed diagnostics?

[Bernd Blaauw]

Op 5-4-2012 5:07, Gene Cumm schreef:

> To my knowledge, adding the "pause" parameter doesn't impact the output
> except for the prompt.

That's the idea, so someone can see the speed results on screen. Not 
that many people have serial consoles or logfiles to store this kind of 
feedback. Without the pause nobody would see results.

> This is extremely common.  I believe I even have a system that went from no
> USB boot to 12Mbps max to 480 Mbps max in its revisions.

My Asus Striker Extreme is still stuck at USB 1.1 unfortunately. Such a 
bootable USB stick with benchmark could check if a machine allows to 
boot from an interface, and if so, at which practical speed.

Likely it will end up like this:
* SATA/SAS: 6gbit max, around 450MB/s in practice if using SSD
* USB2.0  : 480mbit max, around 30 to 45MB per second in practice, if 
not crappy BIOS stuck at 1.1-speeds
* USB3.0  : 5gbit max, not determined if bootable at all, and what BIOS 
speeds (stuck at 1.1-speeds, 2.0-speeds, or some controller-limitation)
* FireWire: 400/800mbit max, only bootable on Apple, even with other 
manufacturers now also using (U)EFI so BIOS no longer an excuse.
* Thunderbolt: 10gbit max, only bootable on Apple, and only in 
target-mode instead of disk-mode? On non-Apple likely just as unbootable 
as Firewire.


> I wrote cptime.c32 for a similar purpose.  It will time how long it takes
> to copy (dump) a file with a bunch of available options (chunk size and max
> length for starters).

Thanks, I'll check that out. It's more generic ofcourse compared to a 
ramdisk program and a bootable disk image.

> Depending on the level of compression, compressibility of data, cpu
> speed/design and other factors, you could see decompression impact ranging
> from negligible to the primary time consumer.

Likely also the reason compression in various Syslinux modules is 
limited to zip/gzip (no 7zip/lzma for example). Time for a .c32 module 
that can load compressed .c32 modules (vesamenu for example) :)

Bernd