advocacy/73646: I/O performance: with/without MEMIO option

Wei-Kai Wu wkwu at
Sun Nov 7 09:40:17 PST 2004

>Number:         73646
>Category:       advocacy
>Synopsis:       I/O performance: with/without MEMIO option
>Confidential:   no
>Severity:       non-critical
>Priority:       low
>Responsible:    freebsd-advocacy
>State:          open
>Class:          change-request
>Submitter-Id:   current-users
>Arrival-Date:   Sun Nov 07 17:40:16 GMT 2004
>Originator:     Wei-Kai Wu
>Release:        FreeBSD 5.2.1-RELEASE amd64
AHA aic7892/7899
AHA aic7901/7902
LSI 1030 Ultra4 Adapter
We ran more than 20000 processes concurrently. Each process requests for
random disk I/O for small files. (reading/writing)

With AHA aic7892/7899 (AHC_ALLOW_MEMIO enabled), the system works well.

With AHA aic7901/7902 (use "ahd" driver), the system works bad.
The console hangs frequently. Each process hangs frequently.

With LSI 1030 (mpt driver), the system works soso.

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