Evgeniy Polyakov, on 12/24/2008 12:38 AM wrote:
On Tue, Dec 23, 2008 at 10:16:25PM +0300, Vladislav Bolkhovitin (vst@xxxxxxxx) 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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