Kallol Biswas wrote:
I have been investigating what the cause of performance loss could be.
I have noticed several things:
0) Setting to CARM_MAX_Q to 30 hangs. So we have been testing only with
CARM_MAX_Q == 1. The firmware has not been updated yet.
Note that CARM_MAX_Q controls the --host-- queue.
This means that, with CARM_MAX_Q==1, only one command can be sent to
--any-- disk, at a time. disks 1-7 must wait for disk 0 to complete an
I/O, and so on. Each command is host-synchronous.
As such, this limits multi-disk performance quite severely, but does not
hamper single disk performance.
CARM_MAX_Q==1 is set as such (as mentioned earlier in the thread)
because early firmwares would lock up if that value was increased.
It has been reported that newer firmwares work fine with CARM_MAX_Q==30,
which completely eliminates the host-synchronous condition.
Jeff
-
To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
the body of a message to [email protected]
More majordomo info at http://vger.kernel.org/majordomo-info.html
Please read the FAQ at http://www.tux.org/lkml/
[Index of Archives]
[Kernel Newbies]
[Netfilter]
[Bugtraq]
[Photo]
[Stuff]
[Gimp]
[Yosemite News]
[MIPS Linux]
[ARM Linux]
[Linux Security]
[Linux RAID]
[Video 4 Linux]
[Linux for the blind]
[Linux Resources]
