[jira] [Updated] (TS-4173) High latency with --enable-linux-native-aio

["Leif Hedstrom (JIRA)" <ji...@apache.org>]

     [ https://issues.apache.org/jira/browse/TS-4173?page=com.atlassian.jira.plugin.system.issuetabpanels:all-tabpanel ]

Leif Hedstrom updated TS-4173:
------------------------------
    Fix Version/s:     (was: 6.2.0)
                   sometime

> High latency with --enable-linux-native-aio
> -------------------------------------------
>
>                 Key: TS-4173
>                 URL: https://issues.apache.org/jira/browse/TS-4173
>             Project: Traffic Server
>          Issue Type: Bug
>          Components: Cache
>            Reporter: Luca Bruno
>             Fix For: sometime
>
>
> Problem:
> My average disk latency on rotational disk with 10000RPM is around 5ms.
> However ATS response times, regardless of having low or high concurrent requests, is on average 20ms.
> The cause:
> With --enable-linux-native-aio, the AIO period time is hardcoded to 10ms (AIO_PERIOD in AIO.cc).
> That's really suboptimal with disk latency that is lower than 10ms. 
> Without --enable-linux-native-aio I get on average 5ms response times which resemble the disk read latency.
> Possible solution:
> Instead of waiting for 10ms unconditionally:
> - Decide (don't know how yet) a number of disk ops NOPS.
> - If the ops queue size >= NOPS, trigger mainAIOEvent, then reset the timer again to AIO_PERIOD.



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