Messages in this thread | | | Date | Wed, 24 Dec 2008 17:37:51 +0300 | From | Vladislav Bolkhovitin <> | Subject | Re: [PATCH][RFC 23/23]: Support for zero-copy TCP transmit of user space data |
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Evgeniy Polyakov, on 12/24/2008 12:38 AM wrote: > On Tue, Dec 23, 2008 at 10:16:25PM +0300, Vladislav Bolkhovitin (vst@vlnb.net) wrote: >> Actually, there's another way, which seems to be a lot simpler. Alexey >> Kuznetsov privately suggested it to me. >> >> In skb_shared_info new pointer transaction_token would be added, which >> would point on: >> >> struct sk_transaction_token >> { >> atomic_t io_count; >> struct sk_transaction_token *next; >> unsigned long token; >> unsigned long private; >> void (*finish_callback)(struct >> sk_transaction_token *); >> }; >> >> When skb is translated, transaction_token inherited. If 2 skb are merged >> (the same places where I put net_get_page's in my patch), the *older* >> token is inherited. This is the main point of this idea. >> >> Before starting new asynchronous send a client would open a new token. >> Everything sent then would receive that token. Finish_callback() would >> be called and the corresponding token freed, when io_count == 0 *AND* >> all previous tokens closed. >> >> This idea seems to be simpler, than even what Rusty implemented. Correct >> me, if I wrong. But, unfortunately, in the near future I will have no >> time to develop it.. :-( > > Yes, it is simpler and cleaner, but it requires additional allocation. > This is additional (and quite noticeble) overhead.
Not necessary requires. For instance, in iscsi-scst sk_transaction_token can (and should) be part of iSCSI cmd structure, so no additional allocations would be needed.
Thanks, Vlad
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