[jira] [Commented] (TS-3044) linux native AIO should use eventfd if available to signal thread

["John Plevyak (JIRA)" <ji...@apache.org>]

    [ https://issues.apache.org/jira/browse/TS-3044?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=14154210#comment-14154210 ] 

John Plevyak commented on TS-3044:
----------------------------------

The perror is from the original AIO_MODE_NATIVE code.   I was just following the style as this was a minimal patch just to add the eventfd handling.   I agree that we should change that to standard ATS errors.  For most unix/linux installations waiting for less than 10msec is the same as waiting for 0msecs, and can result in busy spinning.   The iocore has a minimum wait time, so HRTIME_MSECONDS(4) is disingenuous as well as being a poor idea (if it actually was obeyed).  

> linux native AIO should use eventfd if available to signal thread
> -----------------------------------------------------------------
>
>                 Key: TS-3044
>                 URL: https://issues.apache.org/jira/browse/TS-3044
>             Project: Traffic Server
>          Issue Type: Improvement
>          Components: Cache
>            Reporter: John Plevyak
>            Assignee: Phil Sorber
>             Fix For: 5.2.0
>
>         Attachments: native-aio-eventfd.patch
>
>
> linux native AIO has the ability to signal the event thread to get off the poll and service the disk via the io_set_eventfd() call.  linux native AIO scales better than the thread-based IO, but the current implementation can introduce delays on lightly loaded systems because of the thread is waiting on epoll().   This can be remedied by using io_set_eventfd



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