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Date: Tue, 19 Sep 1995 20:35:03 +1000
From: Bruce Evans <bde@zeta.org.au>
Message-Id: <199509191035.UAA04813@godzilla.zeta.org.au>
To: bde@zeta.org.au, rgrimes@gndrsh.aac.dev.com
Subject: Re: Which SUP files are available and where ?
Cc: current@freebsd.org, rkw@dataplex.net, wollman@lcs.mit.edu
Sender: owner-current@freebsd.org
Precedence: bulk

>> I thought that the CPU ran out of power before the pipe was half full,
>> even doing raw data movement for nfs.

>I have done iozones over NFS on 100BaseTx networking and seen numbers
>well in excess of 3MBytes/s reading (forget about writting, we all
>know sync nfs is dog slow at that).

3MB/s is less than half full.

>> For sup it will have to traverse
>> file systems so it will be hard to get more than 1MB of throughput per
>> file system.

>File system bandwidth is not a problem.  Again, I can produce iozone
>results in excess of 6MB/sec quite easily on local fast disks.

iozone is not representative of anything except huge sequential accesses
to huge sequential files.  On a disk that has an iozone speed of 4-5MB/s
here, the throughput of `cvs -Q co bin' is 30K/sec (2562K, 85.05 real,
12.69 user, 20.96 sys) (the cvs repository is on a separate disk).  The
throughput of `cp -pR bin bin~' is 79K/sec (2562K, 33.41 real, 0.10 user,
3.04 sys).  The throughput of `cp -pR bin separate_slower_disk/bin' is
56K (2562K, 46.50 real, 0.10 user, 3.50 sys).  Abysmal results like this
are typical for accessing small files.

>> Is it as fast as cvs co ;-).

>A _LOT_ faster when you are talking about the two running over local
>ethernet.  NFS gets in the way a bit.  Sup is slow over long RTT links
>due to the 2 RTT needed for many of the things it does, it is blazing
>fast on local networks (and smokes on 100Mb/s networks :-)).

Cancel the previous `;-)'.  sup should be faster than cvs co but it can
hardly be faster than cp -pR, and cp -pR is _slow_.

Bruce