Date: Fri, 21 Dec 2007 00:51:33 +0100 From: Peter Schuller <peter.schuller@infidyne.com> To: Julian Elischer <julian@elischer.org> Cc: freebsd-fs@freebsd.org, ticso@cicely.de, Ivan Voras <ivoras@freebsd.org> Subject: Re: readv: parallel or sequential? Message-ID: <200712210051.41936.peter.schuller@infidyne.com> In-Reply-To: <476AFDBC.9040301@elischer.org> References: <fjbb3v$n60$1@ger.gmane.org> <200712210036.49040.peter.schuller@infidyne.com> <476AFDBC.9040301@elischer.org>
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--nextPart1325381.rZX7Dr3quE Content-Type: text/plain; charset="iso-8859-1" Content-Transfer-Encoding: quoted-printable Content-Disposition: inline > multiple reads and writes to the same file *From different file > descriptors* (same process or not) might proceed in "parallel" but readv > and writev will be implemented serially to the filesystem. now IF THE > FILESYSTEM IS NOT DOING SYNCHRONOUS DISK ACCESSES the reads and writes > might proceed in parallel or be grouped, clustered or otherwise rearanged. If the original claims were just as applied to readv/writev, I don't really= =20 have a problem since there is no guarantee that it will be performed in=20 parallel (though even then, assuming non-synchronous writes, it would=20 certainly be nice if it did pass it along to the device layer in a fashion= =20 that allowed concurrency). But when I/O is clearly being done with the intent of concurrency (by using= =20 AIO or by performing the I/O in different threads/processes), it is more=20 important. =2D-=20 / Peter Schuller PGP userID: 0xE9758B7D or 'Peter Schuller <peter.schuller@infidyne.com>' Key retrieval: Send an E-Mail to getpgpkey@scode.org E-Mail: peter.schuller@infidyne.com Web: http://www.scode.org --nextPart1325381.rZX7Dr3quE Content-Type: application/pgp-signature; name=signature.asc Content-Description: This is a digitally signed message part. -----BEGIN PGP SIGNATURE----- Version: GnuPG v2.0.4 (FreeBSD) iD8DBQBHawANDNor2+l1i30RApKtAJ42aWOvXKnYbC73AoXaZvza/I1MVwCdFei1 0FAfRm9x1swgNtx3YDTVmww= =NQ+4 -----END PGP SIGNATURE----- --nextPart1325381.rZX7Dr3quE--
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