Date: Thu, 16 May 1996 16:48:38 -0700 (PDT) From: Jaye Mathisen <mrcpu@cdsnet.net> To: hackers@freebsd.org Subject: A MMAP observation Message-ID: <Pine.NEB.3.92.960516164342.24704t-100000@schizo.cdsnet.net>
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I've been using MSQL a bit to play around with some stuff, and w/o question, *disabling* mmap() in MSQL lets the application run much faster than *with* mmap. The DB is about 20MB's, and with MMAP (on a 64MB box), it pages a fair amount, and the process gets way up there. W/o mmap, running the same queries and such, the CPU time is way up there, but hardly any paging activity. It also seems to reach a steady state much quicker, where the Wired/Cache/Buf/Free numbers hardly change. I guess w/o more empirical evidence, what it says to me is that at first run, the FreeBSD VM system is doing a darn good job, especially caching. The same app run on BSD/OS just kills it. I don't know why, but there are a few machine differences that may be coming in to play as well. Of course, if somebody would make ODBC clients for FreeBSD so I could let it talk to my NT SQL server, then I wouldn't have to mess with this at all. :)
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