Date: Mon, 10 Mar 2003 10:35:51 +0100 From: Dag-Erling Smorgrav <des@ofug.org> To: msch@snafu.de Cc: Nuno Teixeira <nunotex@aeiou.pt>, freebsd-current@freebsd.org Subject: Re: softupdates && write cache && ata tags topic Message-ID: <xzpisurbm2w.fsf@flood.ping.uio.no> In-Reply-To: <200303081713.50636.msch@snafu.de> (Matthias Schuendehuette's message of "Sat, 8 Mar 2003 17:13:50 %2B0100") References: <200303081713.50636.msch@snafu.de>
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Matthias Schuendehuette <msch@snafu.de> writes:
> I consider it unnecessary to use WriteCache if TaggedQueuing is enabled
> and working.
> (The performace gain of WriteCache and TaggedQueuing is more or less the
> same, the combination of both adds less than 10% of performance and you
> shouldn't use Soft Updates any more)
Write cacheing is automatically enabled if tagged queueing is enabled
and supported by the disk, so I doubt you're seeing any improvement at
all.
/* enable write caching if allowed and not default on device */
if (ata_wc || (ata_tags && ad_tagsupported(adp))) {
if (ata_command(atadev, ATA_C_SETFEATURES,
0, 0, ATA_C_F_ENAB_WCACHE, ATA_WAIT_INTR))
ata_prtdev(atadev, "enabling write cache failed\n");
}
DES
--
Dag-Erling Smorgrav - des@ofug.org
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