Curl's detection of low-speed transfers creates a flood of timeout calls which significantly slows large transfers and increases CPU usage. This is fixed in curl/curl@cacdc27 which is unfortunately not present on EL7.

This PR checks the curl version and only enables the low-speed detection when libcurl is new enough to have the fix.

Trying this patch on a production EL7 xrootd server which handles TPC requests, there was a significant drop in xrootd CPU usage: from ~100% busy, down to ~5%.

To see if the system is likely being affected, look for the function Curl_speedcheck appearing frequently in the gstack output for xrootd.

You can view, comment on, or merge this pull request online at:

  https://github.com/xrootd/xrootd/pull/941

Commit Summary

File Changes

Patch Links:

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