Users can write to a page while we are sending it and making
digest calculations. This ends up causing us to retry the command
when a digest error is later reported. By using sock_no_sendpage
when data digests are calculated we can avoid a lot of (not all but it
helps) the retries becuase sock_no_sendpage is not zero copy.
Signed-off-by: Alex Aizman <itn780@yahoo.com>
Signed-off-by: Dmitry Yusupov <dmitry_yus@yahoo.com>
Signed-off-by: Mike Christie <michaelc@cs.wisc.edu>
Signed-off-by: James Bottomley <James.Bottomley@SteelEye.com>
the scsi layer is using semaphores in a mutex way, this patch converts
these into using mutexes instead
Signed-off-by: Arjan van de Ven <arjan@infradead.org>
Signed-off-by: James Bottomley <James.Bottomley@SteelEye.com>
This merge is pretty extensive. The conflict is over the new
req->retries parameter, so I had to change the prototype to
scsi_setup_blk_pc_cmnd() and the usage in sd, sr and st.
Signed-off-by: James Bottomley <James.Bottomley@SteelEye.com>
From Wang Zhenyu:
High queue depth was a problem for some targets so make queue_depth adjustable
From Mike Christie
Make default queue_depth a little lower
Signed-off-by: Mike Christie <michaelc@cs.wisc.edu>
Signed-off-by: Alex Aizman <itn780@yahoo.com>
Signed-off-by: Dmitry Yusupov <dmitry_yus@yahoo.com>
Signed-off-by: James Bottomley <James.Bottomley@SteelEye.com>
From tomof@acm.org:
There is one more issue about Equallogic systems. They send
re-direction info with FIN. I think that the kernel module needs to
let iscsid to read data from the socket before killing it.
Signed-off-by: Mike Christie <michaelc@cs.wisc.edu>
Signed-off-by: Alex Aizman <itn780@yahoo.com>
Signed-off-by: Dmitry Yusupov <dmitry_yus@yahoo.com>
Signed-off-by: James Bottomley <James.Bottomley@SteelEye.com>
From: tomof@acm.org
I'm not sure about this. I don't think that NODELAY option hurts
performance. However, open-iscsi does not use MSG_MORE properly with
sendpage, so NODELAY option hurts the open-iscsi performance.
I've attached a patch to fix NODELAY and MSG_MORE problems and the
write performance results with disktest.
I use Opteron boxes connected directly, Chelsio NICs, 1500-byte MTU,
64 KB I/O size, and the iSCSI parameters on open-iscsi web site.
With only NODELAY fix, the performance drops, as you said. On the
other hand, NODELAY and MSG_MORE fixes improve the performance
overall.
Signed-off-by: Alex Aizman <itn780@yahoo.com>
Signed-off-by: Dmitry Yusupov <dmitry_yus@yahoo.com>
Signed-off-by: Mike Christie <michaelc@cs.wisc.edu>
Signed-off-by: James Bottomley <James.Bottomley@SteelEye.com>
