AHCI performance and IRQ load

Hi all,

we are currently working on a high performance storage test solution using SATA/AHCI. Due to having performance issues with small block sizes (high interrupt load), we did some research and came across a FAST12 paper by Intel: "When Poll is Better than Interrupt". The authors do suggest a synchronous completion model or even a hybrid mode with support for async and sync completion - for future SSDs.

Does anybody know, if there already is work going on to incorporate such functionality into the block layer & backends (meaning, among others: libata/ahci)?

Another thing, which seemed promising was AHCI's CommandCompletionCoalescing (CCC) feature. However most AHCI controllers don't seem to support this feature. Anybody aware of AHCI controllers having CCC support?

There seemed to be a discussion about CCC support for the ahci driver some years ago http://www.spinics.net/lists/linux-ide/msg02994.html, but obviously no code came out of it - or is there a known patchset?

Thanks,

Joachim Förster
Direct DE: +49 (731) 141-149-42

Missing Link Electronics
http://www.missinglinkelectronics.com
Office DE: +49 (731) 141-149-0
Office US: +1  (408) 457-0700

2012/11/24 Joachim Foerster <[email protected]>:

Hi,

Maybe patchset ---- x86, MSI, AHCI: Support multiple MSIs should help in your case.

regards!

Jack