Messages in this thread | | | Date | Wed, 24 Dec 2008 20:46:56 +0300 | From | Vladislav Bolkhovitin <> | Subject | Re: [PATCH][RFC 23/23]: Support for zero-copy TCP transmit of user space data |
| |
Evgeniy Polyakov, on 12/24/2008 05:44 PM wrote: > On Wed, Dec 24, 2008 at 05:37:51PM +0300, Vladislav Bolkhovitin (vst@vlnb.net) wrote: >>> 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. > > This is special case, I'm not sure it is always possible to cache that > token and attach to every skb, but if it can be done, then of course > this does not end up with additional overhead.
I think in most cases there would be possibility to embed sk_transaction_token to some higher level structure. E.g. Xen apparently should have something to track packets passed through host/guest boundary. From other side, kmem cache is too well polished to have much overhead. I doubt, you would even notice it in this application. In most cases allocation of such small object in it using SLUB is just about the same as a list_del() under disabled IRQs.
Vlad
| |