Date: Thu, 17 Jan 2002 17:20:20 -0800 (PST) From: k Macy <kip_macy@yahoo.com> To: Terry Lambert <tlambert2@mindspring.com>, Julian Elischer <julian@elischer.org> Cc: alc@imimic.com, freebsd-current@freebsd.org, Doug White <dwhite@resnet.uoregon.edu>, k Macy <kip_macy@yahoo.com>, freebsd-hackers@FreeBSD.ORG Subject: -CURRENT AIO bug Re: How well does EVFILT_AIO work? Message-ID: <20020118012020.97262.qmail@web14008.mail.yahoo.com> In-Reply-To: <3C4236D0.77A21A14@mindspring.com>
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It turns that this problem is specific to AIO in -CURRENT. I wrote a simple program that uses the three different completion mechanisms (polling with aio_error, polling with kevent, and using SIGIO) to fill up a file by writing 8kb at a time to the file and then reading 8kb at a time from the file. The lower the average latency, the more frequently it can send off a new request. It can be found at: http://www.eventdriven.org/aio_lat_test.tgz Don't try using the aiotest_sigio (on FreeBSD), the siginfo_t doesn't get filled. Yet another PR that I have to file. Here are the results (in ms): 10 32MB files 4-way Sun server over NFS Memory: 4096M real, 924M free, 768M swap in use, 7234M swap free > uname -a SunOS orbit 5.8 Generic_108528-11 sun4u sparc SUNW,Ultra-Enterprise > ./aiotest_sigio write sk_msecs: 112350 max_latency: 560 reads sk_msecs: 119670 max_latency: 780 > ./aiotest_aio_error write sk_msecs: 45570 max_latency: 240 reads sk_msecs: 48280 max_latency: 630 > ./aiotest_sigio write sk_msecs: 117260 max_latency: 410 reads sk_msecs: 124100 max_latency: 600 > ./aiotest_aio_error write sk_msecs: 45050 max_latency: 780 reads sk_msecs: 46550 max_latency: 1530 10 32MB files 600Mhz Laptop local disk UDMA33 Mem: 68M Active, 134M Inact, 30M Wired, 15M Cache, 35M Buf, 656K Free kmacy@netherworld [15:20][~/src/bugs] uname -a FreeBSD netherworld.eventdriven.org 4.5-RC FreeBSD 4.5-RC #1: Wed Jan 16 21:30:55 PST 2002 root@netherworld.e ventdriven.org:/usr/src/sys/compile/NETHERWORLD i386 kmacy@netherworld [15:08][~/src/bugs/aio] ./aiotest_aio_error write sk_msecs: 72890 max_latency: 930 reads sk_msecs: 56830 max_latency: 930 kmacy@netherworld [15:11][~/src/bugs/aio] ./aiotest_kevent write sk_msecs: 71300 max_latency: 1380 reads sk_msecs: 54500 max_latency: 1380 kmacy@netherworld [15:14][~/src/bugs/aio] ./aiotest_aio_error write sk_msecs: 73970 max_latency: 990 reads sk_msecs: 56790 max_latency: 990 kmacy@netherworld [15:17][~/src/bugs/aio] ./aiotest_kevent write sk_msecs: 73620 max_latency: 980 reads sk_msecs: 59620 max_latency: 1860 2-way 1.0GHZ FreeBSD weizen.extendedsolutions.com 5.0-20020106-CURRENT FreeBSD 5.0-20020106-CURRENT #3: Thu Jan 10 18:58:36 PS T 2002 root@weizen.extendedsolutions.com:/usr/src/sys/i386/compile/HADES i386 Mem: 11M Active, 188M Inact, 111M Wired, 1760K Cache, 111M Buf, 691M Free (~420x slower) (~420x slower) 10 1MB files local disk (UDMA33) > aiotest_aio_error write sk_msecs: 959540 max_latency: 29960 reads sk_msecs: 959970 max_latency: 29960 Same machine compiled UP: > aiotest_aio_error write sk_msecs: 810010 max_latency: 29960 reads sk_msecs: 779950 max_latency: 29960 > uname -a FreeBSD weizen.extendedsolutions.com 5.0-20020106-CURRENT FreeBSD 5.0-20020106-CURRENT #0: Thu Jan 17 15:36:56 PS T 2002 root@weizen.extendedsolutions.com:/usr/src/sys/i386/compile/HADES_UP i386 --- Terry Lambert <tlambert2@mindspring.com> wrote: > Julian Elischer wrote: > > the threads package doesn't do file IO > asynchronoulsy > > in fact there ahve been several people > threatenning to use AIO > > to make the threads package to that asychronously > too. > > Which is incredibly funny, if you think about it, > since there > are two ways to implement a call conversion threads > package: > > 1) Trade a sync call for an async call plus a > context > switch > > 2) Trade a blocking call for a non-blocking call > plus > a context switch > > So... how do you do a non-blocking aio_wait again? > 8-) 8-). > > -- Terry __________________________________________________ Do You Yahoo!? Send FREE video emails in Yahoo! Mail! http://promo.yahoo.com/videomail/ To Unsubscribe: send mail to majordomo@FreeBSD.org with "unsubscribe freebsd-hackers" in the body of the message
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