Messages in this thread | | | Date | Tue, 16 Apr 2002 11:20:24 +0900 (JST) | Subject | Re: [PATCH] zerocopy NFS updated | From | Hirokazu Takahashi <> |
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Hi,
jakob> Won't this serialize too much ? I mean, consider the situation where we jakob> have file-A and file-B completely in cache, while file-C needs to be jakob> read from the physical disk. jakob> jakob> Three different clients (A, B and C) request file-A, file-B and file-C jakob> respectively. The send of file-C is started first, and the sends of files jakob> A and B (which could commence immediately and complete at near wire-speed) jakob> will now have to wait (leaving the NIC idle) until file-C is read from jakob> the disks. jakob> jakob> Even if it's not the entire file but only a single NFS request (probably 8kB), jakob> one disk seek (7ms) is still around 85 kB, or 10 8kB NFS requests (at 100Mbit). jakob> jakob> Or am I misunderstanding ? Will your UDP sendpage() queue the requests ?
No problem. On my implementation, at the beginning a knfsd grabs all pages -- a part of file-C -- to reply to the NFS client. After that the knfsd starts to send them. It won't block any other knfsds during disk I/Os.
Thank you, Hirokazu Takahashi.
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