mirror of https://github.com/BOINC/boinc.git
60 lines
2.5 KiB
HTML
60 lines
2.5 KiB
HTML
<title>Measuring and distinguishing hosts</title>
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<body bgcolor=ffffff>
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<h2>Measuring and distinguishing hosts</h2>
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<p>
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The core client measures the following aspects of each host:
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<ul>
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<li> <b>CPU performance</b>: integer ops/sec, double-precision
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floating-point ops/sec, and memory bandwidth are measured separately.
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They are measured by a process executing at the same priority as BOINC
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applications, so the results will be affected by other processes.
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These measurements are taken when the client starts for the first time,
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and once every month afterwards.
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<li> <b>Number of CPUs</b>: By default, the number of simultaneous
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slot directories will be set to this number unless otherwise indicated
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by user preferences.
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<li> <b>Vendor and model of CPU</b>
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<li> <b>Disk space</b>: free space and total space on the drive which
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BOINC is installed on.
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These numbers will be used to ensure BOINC does
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not use more space than set in the user preferences.
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<li> <b>Memory</b>: total RAM, CPU cache, and swap space.
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These numbers can be used by the scheduling server to decide whether or not to
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assign work to a client.
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This also provides a means for assignment of
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differing work based on host abilities.
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<li> <b>Timezone</b>:
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<li> <b>Last IP address</b> and count of consecutive same addresses.
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<li> <b>Number of RPCs and time of last RPC</b>.
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<li> <b>Fractions of time</b> that core client runs on host, host is
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connected, and user is active.
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These are computed as exponentially-weighted averages; see the class TIME_STATS.
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<li> <b>Operating system name and version</b>.
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<li> <b>Average up- and downstream network bandwidth</b>.
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These are computed as exponentially-weighted averages; see the class NET_STATS.
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</ul>
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These quantities are reported in every scheduling RPC, and their latest
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values are stored in the BOINC database.
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<h3>Distinguishing hosts</h3>
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<p>
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Not all systems have an application-readable globally unique ID, so
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we don't take this approach.
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When a host first contacts the scheduling
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server it is assigned a host ID, which it stores in its
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<tt>client_state.xml</tt> file.
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<p>
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The BOINC database maintains the RPC sequence number for each host,
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and the host maintains the sequence number in its
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<tt>client_state.xml</tt> file.
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<p>
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To install the BOINC client on a large number of computers, users
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are instructed to copy only the executable and the <tt>prefs.xml</tt> file.
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If the user copies the <tt>client_state.xml</tt> file as well, the
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first RPCs from the other hosts will have a repeat sequence number;
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in this case the scheduling server creates a new host record and returns
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its ID.
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