Date: Mon, 21 Jan 2013 20:15:47 +0530 From: "Desai, Kashyap" <Kashyap.Desai@lsi.com> To: "freebsd-scsi@freebsd.org" <freebsd-scsi@freebsd.org> Cc: "Kenneth D. Merry" <ken@FreeBSD.org>, "jhb@freebsd.org" <jhb@freebsd.org>, "McConnell, Stephen" <Stephen.McConnell@lsi.com> Subject: Max Queue depth of HBA limited to 256 ? Message-ID: <B2FD678A64EAAD45B089B123FDFC3ED75E68FD6158@inbmail01.lsi.com>
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Hi,
I was trying to check few things on LSI controller, where we have more than 256 queue depth support.
I added default maxtags in scsi/scsi_xpt.c as below. (Because I don't want mattags to restrict any outstanding commands the LSI HBA.
{
/* Default tagged queuing parameters for all devices */
{
T_ANY, SIP_MEDIA_REMOVABLE|SIP_MEDIA_FIXED,
/*vendor*/"*", /*product*/"*", /*revision*/"*"
},
/*quirks*/0, /*mintags*/2, /*maxtags*/1024 <--- Default maxtags were 256. I increase it to 10234
},
LSI's SAS-HBA and MR-HBA can support more than 256 outstanding commands in Firmware. But due to some reason, I am not able to pump more than 256 outstanding commands to the HBA.
I used "rawio -p 256 /dev/da1" and more /dev/dax in loop. I have sysctl parameter in Driver to display outstanding "FW commands". Max value for FW outstanding only goes up to 256.
Also from some other mail thread Subject "mfi driver performance", I found that folks talk about tuning queue depth _but_ nobody discussed to increase it beyond 256. Is there any limitation in FreeBSD ?
~ Kashyap
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