Date: Sun, 30 Oct 2011 22:44:43 +1100 From: Adrian Chadd <adrian@freebsd.org> To: lev@freebsd.org Cc: arch@freebsd.org Subject: Re: [PATCH] fadvise(2) system call Message-ID: <CAJ-VmomdJnGqgRWH9zop=Opc=B6MxhCnL%2B1LSroUo3Np7LJNQg@mail.gmail.com> In-Reply-To: <908954806.20111030130143@serebryakov.spb.ru> 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> <908954806.20111030130143@serebryakov.spb.ru>
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On 30 October 2011 20:01, Lev Serebryakov <lev@freebsd.org> wrote: > =A0 I don't know. But I could show your results of typical ktrace, where > =A0transmission-daemon spends 590 seconds of 600 (Wall time) in > =A0pread() syscall , and real read speed is only about 30Mbit/s (and > =A0this FS could be read at speed about 300MiB/s, 100 times faster, > =A0with linear read). Is the app doing multi-threaded disk IO? How random is the IO? How is fadvise being used in the torrent client? Is it being used to force in data into cache? I'm not knocking the fadvise work (far from it!), I'd just like to better understand what's going on here. adrian
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