From: john smith <whalajam@yahoo.com>
To: linux-scsi@vger.kernel.org
Subject: scsi_host_template.queuecommand() instances
Date: Sun, 27 Feb 2011 11:22:06 -0800 (PST) [thread overview]
Message-ID: <304254.22314.qm@web161906.mail.bf1.yahoo.com> (raw)
I understand that inside LDD's scsi_host_template.queuecommand(), the card->spinlock can be used to protect shared data between concurrent instances of queuecommand and bottom-half/tasklets IO completion code.
For SMP system with PCIE/MSIX enabled interrupts, there can be multiple instances of completion tasklets.
The questions I have are:
- can there be multiple instances of queuecommand as well?
- if so, I would assume they are IO commands issued for different targets (controlled by LDD), correct?
Also, if true, these multiple instances must be running on different kernel threads spwaned by the SCSI mid layer, or block layer?
Links to detailed and uptodate Block layer description would be appreciated (the ones I found are either old and superficial),
thanks,
John
next reply other threads:[~2011-02-27 19:28 UTC|newest]
Thread overview: 7+ messages / expand[flat|nested] mbox.gz Atom feed top
2011-02-27 19:22 john smith [this message]
2011-02-27 22:21 ` scsi_host_template.queuecommand() instances Matthew Wilcox
2011-02-28 7:21 ` john smith
2011-02-28 13:24 ` Matthew Wilcox
2011-02-28 14:14 ` James Bottomley
2011-03-08 18:22 ` john smith
2011-03-04 20:58 ` john smith
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