From mboxrd@z Thu Jan 1 00:00:00 1970 From: Roman Mamedov Subject: Re: Rename BTRfs to MuchSlowerFS ? Date: Mon, 5 Sep 2011 20:20:00 +0600 Message-ID: <20110905202000.4c539297@natsu> References: <4E64D3D5.7020407@petaramesh.org> <20110905140023.GP9907@carfax.org.uk> Mime-Version: 1.0 Content-Type: multipart/signed; micalg=PGP-SHA1; boundary="Sig_/Gcvx.H85=.nkDYQt_JVx+eq"; protocol="application/pgp-signature" Cc: =?UTF-8?B?U3fDom1p?= Petaramesh , linux-btrfs To: Hugo Mills Return-path: In-Reply-To: <20110905140023.GP9907@carfax.org.uk> List-ID: --Sig_/Gcvx.H85=.nkDYQt_JVx+eq Content-Type: text/plain; charset=US-ASCII Content-Transfer-Encoding: quoted-printable On Mon, 5 Sep 2011 15:00:23 +0100 Hugo Mills wrote: > >=20 > > BTRFS machine took 20 HOURS so far, still counting (ETA 15 minutes left= ). > >=20 > > Wow. Impressive. >=20 > That's because dpkg is known for using (f)sync very heavily. btrfs > honours the sync request in all cases I don't think it's *just* that. I had the same problem, recently upgrading Debian from Stable to Testing, i= t was taking more than 24 hours. I stopped the upgrade, then resumed it thi= s time via eatmydata, and it proceeded perhaps two orders of magnitude fast= er than before, finishing the remaining packages in 5 minutes or so. Problem is, even when I stopped the upgrade and waited a considerable time,= each 'sync' was still taking 5-7 seconds. No other disk activity in the sy= stem, no snapshot creation/deletion/cleanup going on either, just multiple = consecutive syncs: rm@rm:~$ time sync real 0m4.772s user 0m0.000s sys 0m0.480s rm@rm:~$ time sync real 0m6.831s user 0m0.000s sys 0m0.472s rm@rm:~$ time sync real 0m8.069s user 0m0.000s sys 0m0.468s rm@rm:~$ time sync real 0m6.675s user 0m0.000s sys 0m0.464s rm@rm:~$ time sync real 0m4.293s user 0m0.000s sys 0m0.464s rm@rm:~$ time sync real 0m4.230s user 0m0.000s sys 0m0.472s rm@rm:~$ time sync real 0m6.924s user 0m0.000s sys 0m0.464s To be fair, this was on the 2.6.39.2 kernel, and the performance seems to b= e somewhat better on 3.0 (though I didn't do tests like this one or any sig= nificant dpkg operations on it yet). --=20 With respect, Roman --Sig_/Gcvx.H85=.nkDYQt_JVx+eq Content-Type: application/pgp-signature; name=signature.asc Content-Disposition: attachment; filename=signature.asc -----BEGIN PGP SIGNATURE----- Version: GnuPG v1.4.11 (GNU/Linux) iEYEARECAAYFAk5k2pAACgkQTLKSvz+PZwj/hQCaAl8trEpePslkwUzAVQDCsAKP DLIAnRE9x+BcaDdgzF8Q/O/ATPDxhVuM =fKnd -----END PGP SIGNATURE----- --Sig_/Gcvx.H85=.nkDYQt_JVx+eq--