* iSCSI and scatterlists [not found] ` <42387EA2.5020106@us.ibm.com> @ 2005-03-16 18:53 ` Matthew Wilcox 2005-03-16 19:59 ` Dmitry Yusupov 0 siblings, 1 reply; 2+ messages in thread From: Matthew Wilcox @ 2005-03-16 18:53 UTC (permalink / raw) To: Mike Christie Cc: Jens Axboe, Christoph Hellwig, Matthew Wilcox, James Bottomley, SCSI Mailing List, netdev On Wed, Mar 16, 2005 at 10:44:50AM -0800, Mike Christie wrote: > I got lost here. If you are talking about the need to kmap a sglist then > software iscsi has it. iscsi-sfnet used to do > > while (...) > kmap() > > but I fixed that (I think I need to use kmap_atomic though, is that > correct or is it just a performance improvement - I am calling kmap from > a thread too so). I just added kmap_atomic to open-iscsi and I believe > pyx does something similar to the loop above. Sounds like networking should grow an interface to accept a sglist as input. I'm really not familiar with Linux's networking stack to know how to do it ... cc'ing netdev to get their thoughts. -- "Next the statesmen will invent cheap lies, putting the blame upon the nation that is attacked, and every man will be glad of those conscience-soothing falsities, and will diligently study them, and refuse to examine any refutations of them; and thus he will by and by convince himself that the war is just, and will thank God for the better sleep he enjoys after this process of grotesque self-deception." -- Mark Twain ^ permalink raw reply [flat|nested] 2+ messages in thread
* Re: iSCSI and scatterlists 2005-03-16 18:53 ` iSCSI and scatterlists Matthew Wilcox @ 2005-03-16 19:59 ` Dmitry Yusupov 0 siblings, 0 replies; 2+ messages in thread From: Dmitry Yusupov @ 2005-03-16 19:59 UTC (permalink / raw) To: Matthew Wilcox Cc: Mike Christie, Jens Axboe, Christoph Hellwig, James Bottomley, SCSI Mailing List, netdev, open-iscsi On Wed, 2005-03-16 at 18:53 +0000, Matthew Wilcox wrote: > On Wed, Mar 16, 2005 at 10:44:50AM -0800, Mike Christie wrote: > > I got lost here. If you are talking about the need to kmap a sglist then > > software iscsi has it. iscsi-sfnet used to do > > > > while (...) > > kmap() > > > > but I fixed that (I think I need to use kmap_atomic though, is that > > correct or is it just a performance improvement - I am calling kmap from > > a thread too so). I just added kmap_atomic to open-iscsi and I believe > > pyx does something similar to the loop above. > > Sounds like networking should grow an interface to accept a sglist as > input. I'm really not familiar with Linux's networking stack to know > how to do it ... cc'ing netdev to get their thoughts. This is a nice idea, but will not always work with iSCSI protocol simply because iSCSI PDU's data sizes might be negotiated to be lesser/bigger than original WRITE's sglist size. It might help to optimize some data path when PDU's data segment size >= sglist size. i.e. entire sglist needs to be passed down to the stack. i'm cross-posting to open-iscsi mailing list, so open-iscsi folks might participate in the discussion. Dmitry ^ permalink raw reply [flat|nested] 2+ messages in thread
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2005-03-16 18:53 ` iSCSI and scatterlists Matthew Wilcox
2005-03-16 19:59 ` Dmitry Yusupov
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