Date: Sun, 30 Oct 2011 13:01:43 +0400 From: Lev Serebryakov <lev@FreeBSD.org> To: Adrian Chadd <adrian@freebsd.org> Cc: arch@freebsd.org Subject: Re: [PATCH] fadvise(2) system call Message-ID: <908954806.20111030130143@serebryakov.spb.ru> In-Reply-To: <CAJ-Vmo=D-b1SJ0WjJGGJ_WPK8FvE-fptDPRCGyMVhOm=FR8RYA@mail.gmail.com> References: <201110281426.00013.jhb@freebsd.org> <4EAB550E.3060603@FreeBSD.org> <458756137.20111030024046@serebryakov.spb.ru> <CAJ-Vmo=D-b1SJ0WjJGGJ_WPK8FvE-fptDPRCGyMVhOm=FR8RYA@mail.gmail.com>
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Hello, Adrian. You wrote 30 =D0=BE=D0=BA=D1=82=D1=8F=D0=B1=D1=80=D1=8F 2011 =D0=B3., 4:05:= 19: >>>> You can read the description of posix_fadvise() (which this implements= ) here: >>> If you want a real-world consumer of posix_fadvise you can take a look >>> at net-p2p/libtorrent-rasterbar15. The code is ifdef'ed out for FreeBSD >>> because we don't have that yet, but it should be obvious how to >>> re-enable it. There are a few clients that use that lib, qbittorrent is >>> probably the most straightforward. >> =C2=A0net-p2p/transmission-daemon could be used, too. It shows very poor >> performance on UFS (90% in pread() call and 50% of wall time to >> saturate 40Mbit/s channel from fast disk) compared to Linux, where >> such interface exists. > ... why? Squid/Lusca doesn't suffer that way. I don't know. But I could show your results of typical ktrace, where transmission-daemon spends 590 seconds of 600 (Wall time) in pread() syscall , and real read speed is only about 30Mbit/s (and this FS could be read at speed about 300MiB/s, 100 times faster, with linear read). --=20 // Black Lion AKA Lev Serebryakov <lev@FreeBSD.org>
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