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

[Wei-Kai Wu]

>Number:         73646
>Category:       advocacy
>Synopsis:       I/O performance: with/without MEMIO option
>Confidential:   no
>Severity:       non-critical
>Priority:       low
>Responsible:    freebsd-advocacy
>State:          open
>Quarter:        
>Keywords:       
>Date-Required:
>Class:          change-request
>Submitter-Id:   current-users
>Arrival-Date:   Sun Nov 07 17:40:16 GMT 2004
>Closed-Date:
>Last-Modified:
>Originator:     Wei-Kai Wu
>Release:        FreeBSD 5.2.1-RELEASE amd64
>Organization:
Kavalan
>Environment:
AHA aic7892/7899
AHA aic7901/7902
LSI 1030 Ultra4 Adapter
>Description:
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.
>How-To-Repeat:
>Fix:
>Release-Note:
>Audit-Trail:
>Unformatted: