Messages in this thread | | | Date | Mon, 22 Jan 2001 13:00:08 +0000 (GMT) | From | James Sutherland <> | Subject | Re: Is sendfile all that sexy? |
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On Mon, 22 Jan 2001, Helge Hafting wrote:
> And when the next user wants the same webpage/file you read it from > the RAID again? Seems to me you loose the benefit of caching stuff in > memory with this scheme. Sure - the RAID controller might have some > cache, but it is usually smaller than main memory anyway.
Hrm... good point. Using "main memory" (whose memory, on a NUMA box??) as a cache could be a performance boost in some circumstances. On the other hand, you're eating up a chunk of memory bandwidth which could be used for other things - even when you only cache in "spare" RAM, how do you decide who uses that RAM - and whether or not they should?
There certainly comes a point at which not caching in RAM would be a net win, but ATM the kernel doesn't know enough to determine this.
On a shared bus, probably the best solution would be to have the data sent to both devices (NIC and RAM) at once?
> And then there are things like retransmissions...
Hopefully handled by an intelligent NIC in most cases; if you're caching the file in RAM as well (by "CCing" the data there the first time) this is OK anyway.
Something to think about, but probably more on-topic for linux-futures I suspect...
James.
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