update SSK latency/creation-time graph links
[Imported from Trac: page Performance, version 26]
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@ -61,9 +61,6 @@ The munin
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[/tahoe-figleaf-graph/hanford.allmydata.com-tahoe_speedstats_delay.html delay graph] and
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[/tahoe-figleaf-graph/hanford.allmydata.com-tahoe_speedstats_rate.html rate graph] show these Ax+B numbers for a node in colo and a node behind a DSL line.
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The [/tahoe-figleaf-graph/hanford.allmydata.com-tahoe_speedstats_delay_SSK.html mutable-file delay graph] shows the "B" per-file latency number
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for mutable (aka "SSK") files. In the 0.7.0 release, this is dominated by the RSA keypair generation necessary to create each new mutable file.
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The
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[/tahoe-figleaf-graph/hanford.allmydata.com-tahoe_speedstats_delay_rtt.html delay*RTT graph] shows this per-file delay as a multiple of the average round-trip
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time between the client node and the testnet. Much of the work done to upload
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@ -71,6 +68,24 @@ a file involves waiting for message to make a round-trip, so expressing the
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per-file delay in units of RTT helps to compare the observed performance
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against the predicted value.
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### Mutable Files
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Tahoe's mutable files (sometimes known as "SSK" files) are encoded
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differently than the immutable ones (aka "CHK" files). Creating these mutable
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file slots currently (in release 0.7.0) requires an RSA keypair generation.
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[This graph](http://allmydata.org/tahoe-figleaf-graph/hanford.allmydata.com-tahoe_speedstats_SSK_creation.html)
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tracks the amount of time it takes to perform
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this step.
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There is also per-file overhead for upload and download, just like with CHK
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files, mostly involving the queries to find out which servers are holding
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which versions of the file. The
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[/tahoe-figleaf-graph/hanford.allmydata.com-tahoe_speedstats_delay_SSK.html mutable-file delay graph]
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shows this "B" per-file latency value.
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The "A" transfer rate for SSK files is also tracked. TODO: add a link to the
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graph.
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### Roundtrips
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The 0.5.1 release requires about 9 roundtrips for each share it uploads. The
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