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Mon, 6 Jul 2020 02:17:17 -0400 Received: from mout.gmx.net ([212.227.17.20]:50405 "EHLO mout.gmx.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1728804AbgGFGRR (ORCPT ); Mon, 6 Jul 2020 02:17:17 -0400 DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=gmx.net; s=badeba3b8450; t=1594016223; bh=mKodQ0Y23blwZ4y+cpLZtdo8358ICaHyf4ytArKLYuU=; h=X-UI-Sender-Class:Subject:To:References:From:Date:In-Reply-To; b=TE+vS5op6OSOVP8PF836wTL9chimcORF7ksTKKVzTuJIuH1aQc7J4OfLgC12u8xLk JqUYWEXLsaOzot6d3gaPnYitWzSIoGvcOPbl84NgHJv/qgVCYCnyWhvlVwKHtu8Nxt 5sBP6B7vXchlk71cvsnyxXC0ovlyoKReOgKAOorY= X-UI-Sender-Class: 01bb95c1-4bf8-414a-932a-4f6e2808ef9c Received: from [0.0.0.0] ([149.28.201.231]) by mail.gmx.com (mrgmx105 [212.227.17.174]) with ESMTPSA (Nemesis) id 1N1OXT-1ktgdJ1DVz-012mXL; Mon, 06 Jul 2020 08:17:02 +0200 Subject: Re: [PATCH] btrfs: speedup mount time with force readahead chunk tree To: Robbie Ko , linux-btrfs@vger.kernel.org References: <20200701092957.20870-1-robbieko@synology.com> From: Qu Wenruo Autocrypt: addr=quwenruo.btrfs@gmx.com; 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Linux x86_64; rv:68.0) Gecko/20100101 Thunderbird/68.9.0 MIME-Version: 1.0 In-Reply-To: Content-Type: multipart/signed; micalg=pgp-sha256; protocol="application/pgp-signature"; boundary="mlRMY68DA2QAMmYm2zqnAD6NEE3Vsmjkt" X-Provags-ID: V03:K1:+DunM0UKVFzsxHGls8tIeUvVO6Zfk/DDFH6035FbcONWi2im0Lv O+fOv7X6OxVMpZZmhlRfRtOyNRi97d5PyyP6hYSn4blrcXBkMrC4KUIZ4YHb0O/zpfdkGBL 9LPdS+D7XbV22wtonT5oH40aQYiV3Lg5rL9h3ieh7HlAG4drv2dIm+26TAK5qMkugeqiuz5 imWhBFgrrdcMR3D7zDbrw== X-UI-Out-Filterresults: notjunk:1;V03:K0:mEnrtRT76bg=:DifVa3xgVw1AqK/Snn3MDT +X/lEsQUHQrR4lh/4LvLO4dgB3eXjgJSfXOe+RFmDZhDMToM8rnX+iy+NdvRA5QFVzb+Xu5o/ j0Pn0dyolBV7Pbe1slwhbpFYbYQszszHry1J8dOdKEbz8SBIOl2r8pDMfHhGxswDBVT6mxllN XOSOhCxjYNRJx+GbgQeY+j2JPO1ucuk3kw7XchbCcCaiOaeBryO4ek23KxLN8+1qdAzYytFZ/ FvgFPKFHv+wLo9k5Evxm0F7K3d5Cu1yoLU90KG+cyDzoH4B0jtzsetJgOU9su1ITt7i3GHUGK Wtr4wV5v58z/kwAFD+KWuaL+a78dfQ38C4KdPg5EeM9kqbSC8KmSShcqhRftm5iAFqNumRgbe +NFBe9RtTgxWDJEcuN7TH0SCumZkFx5j7gTsp15rptJWjBHwhSOWl+lsicU8C9YUvxT07UR+v iz1cSrltTGAe0kmFUkAwoCvzR+SoBAqk4aWtLfyWNxfcS0nXarr8lykDDGCHPJwkatKZYwsNs HfzVnx0EdsTX2l1qxdPi7Qe9aKDioIu4dI2ofp4gOuoHClfibl33eDvDfFLRnQn9YwV02o3eU FeB13BjnT0Be/dRa66oENRjoCBak8OUR8OfkaR6qrhpdMs9KMi/FjC937KEMrkrOwoKL5LQjZ nUwxIyBYaQdZWtC4OUv1nGH8dxrQqXcCZyOlMRTM3E76MtwOiS0UGJjSqQfZS5rPyYaSbjVzg dhqh9CvmUsma35VYsK3kl94kTq7K+XSU+d2kuxw500u/JNIQrwMcrqgp2CZl5N4WnZ7vIdDd1 j+UBLRPA1msIFJkLKcrUYoMSZacZpvFXX80ftsNml8YCKpSr1jbKXFduoDok5kG6IavE8Y558 7pFGkGuoSYYHM8vHqXLf89GKfe0O5zND+Ti8+gIUm5YhSEApwNfvoA2TKAu3ZmkmUYUgB7Dft Y1zrCsFtXdXedjhMe084jMtIvc8dilkgIMcXjlHoaB1+LnlgvZ89sooDLFVVqoNNpWJ7d5Yn2 YAv3G0k7kXiCKu97Kg2d/4eBmT5XYRWKgMUR9OcCPQu8b3LGcXLxV+M+whwW7mttk6avDvQ6c tnEtq53X3PmYkzdOBaFiBWelmc00xmz42kWF63azRPSn2KblvvZMqCF1weQBapwVcEEzNCQgj Ff7GCVxZzwKKDKTRaV2ggKW0e+Pgx/E4+blBOMs91kRfqWqQPZFEJg/m7Q0SWHSdKYfmWOAqT fvx04n42/YwxIEOKY Sender: linux-btrfs-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-btrfs@vger.kernel.org This is an OpenPGP/MIME signed message (RFC 4880 and 3156) --mlRMY68DA2QAMmYm2zqnAD6NEE3Vsmjkt Content-Type: multipart/mixed; boundary="PSLQ3v73p37nWbgPX258oxqYERoXR9xnL" --PSLQ3v73p37nWbgPX258oxqYERoXR9xnL Content-Type: text/plain; charset=utf-8 Content-Language: en-US Content-Transfer-Encoding: quoted-printable On 2020/7/6 =E4=B8=8B=E5=8D=882:13, Robbie Ko wrote: > Does anyone have any suggestions? I believe David's suggestion on using regular readahead is already good enough for chunk tree. Especially since chunk tree is not really the main cause for slow mount. Thanks, Qu >=20 > robbieko =E6=96=BC 2020/7/1 =E4=B8=8B=E5=8D=885:29 =E5=AF=AB=E9=81=93: >> From: Robbie Ko >> >> When mounting, we always need to read the whole chunk tree, >> when there are too many chunk items, most of the time is >> spent on btrfs_read_chunk_tree, because we only read one >> leaf at a time. >> >> We fix this by adding a new readahead mode READA_FORWARD_FORCE, >> which reads all the leaves after the key in the node when >> reading a level 1 node. >> >> Signed-off-by: Robbie Ko >> --- >> =C2=A0 fs/btrfs/ctree.c=C2=A0=C2=A0 | 7 +++++-- >> =C2=A0 fs/btrfs/ctree.h=C2=A0=C2=A0 | 2 +- >> =C2=A0 fs/btrfs/volumes.c | 1 + >> =C2=A0 3 files changed, 7 insertions(+), 3 deletions(-) >> >> diff --git a/fs/btrfs/ctree.c b/fs/btrfs/ctree.c >> index 3a7648bff42c..abb9108e2d7d 100644 >> --- a/fs/btrfs/ctree.c >> +++ b/fs/btrfs/ctree.c >> @@ -2194,7 +2194,7 @@ static void reada_for_search(struct >> btrfs_fs_info *fs_info, >> =C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0= =C2=A0 if (nr =3D=3D 0) >> =C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0= =C2=A0=C2=A0=C2=A0=C2=A0=C2=A0 break; >> =C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0= =C2=A0 nr--; >> -=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0 } else if (path->reada =3D= =3D READA_FORWARD) { >> +=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0 } else if (path->reada =3D= =3D READA_FORWARD || path->reada =3D=3D >> READA_FORWARD_FORCE) { >> =C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0= =C2=A0 nr++; >> =C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0= =C2=A0 if (nr >=3D nritems) >> =C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0= =C2=A0=C2=A0=C2=A0=C2=A0=C2=A0 break; >> @@ -2205,12 +2205,15 @@ static void reada_for_search(struct >> btrfs_fs_info *fs_info, >> =C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0= =C2=A0=C2=A0=C2=A0=C2=A0=C2=A0 break; >> =C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0 } >> =C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0 search =3D btrf= s_node_blockptr(node, nr); >> -=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0 if ((search <=3D target &&= target - search <=3D 65536) || >> +=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0 if ((path->reada =3D=3D RE= ADA_FORWARD_FORCE) || >> +=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0 (s= earch <=3D target && target - search <=3D 65536) || >> =C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0= =C2=A0 (search > target && search - target <=3D 65536)) { >> =C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0= =C2=A0 readahead_tree_block(fs_info, search); >> =C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0= =C2=A0 nread +=3D blocksize; >> =C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0 } >> =C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0 nscan++; >> +=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0 if (path->reada =3D=3D REA= DA_FORWARD_FORCE) >> +=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0 co= ntinue; >> =C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0 if ((nread > 65= 536 || nscan > 32)) >> =C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0= =C2=A0 break; >> =C2=A0=C2=A0=C2=A0=C2=A0=C2=A0 } >> diff --git a/fs/btrfs/ctree.h b/fs/btrfs/ctree.h >> index d404cce8ae40..808bcbdc9530 100644 >> --- a/fs/btrfs/ctree.h >> +++ b/fs/btrfs/ctree.h >> @@ -353,7 +353,7 @@ struct btrfs_node { >> =C2=A0=C2=A0 * The slots array records the index of the item or block = pointer >> =C2=A0=C2=A0 * used while walking the tree. >> =C2=A0=C2=A0 */ >> -enum { READA_NONE, READA_BACK, READA_FORWARD }; >> +enum { READA_NONE, READA_BACK, READA_FORWARD, READA_FORWARD_FORCE }; >> =C2=A0 struct btrfs_path { >> =C2=A0=C2=A0=C2=A0=C2=A0=C2=A0 struct extent_buffer *nodes[BTRFS_MAX_L= EVEL]; >> =C2=A0=C2=A0=C2=A0=C2=A0=C2=A0 int slots[BTRFS_MAX_LEVEL]; >> diff --git a/fs/btrfs/volumes.c b/fs/btrfs/volumes.c >> index 0d6e785bcb98..78fd65abff69 100644 >> --- a/fs/btrfs/volumes.c >> +++ b/fs/btrfs/volumes.c >> @@ -7043,6 +7043,7 @@ int btrfs_read_chunk_tree(struct btrfs_fs_info >> *fs_info) >> =C2=A0=C2=A0=C2=A0=C2=A0=C2=A0 path =3D btrfs_alloc_path(); >> =C2=A0=C2=A0=C2=A0=C2=A0=C2=A0 if (!path) >> =C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0 return -ENOMEM;= >> +=C2=A0=C2=A0=C2=A0 path->reada =3D READA_FORWARD_FORCE; >> =C2=A0 =C2=A0=C2=A0=C2=A0=C2=A0=C2=A0 /* >> =C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0 * uuid_mutex is needed only if we= are mounting a sprout FS --PSLQ3v73p37nWbgPX258oxqYERoXR9xnL-- --mlRMY68DA2QAMmYm2zqnAD6NEE3Vsmjkt Content-Type: application/pgp-signature; name="signature.asc" Content-Description: OpenPGP digital signature Content-Disposition: attachment; filename="signature.asc" -----BEGIN PGP SIGNATURE----- iQEzBAEBCAAdFiEELd9y5aWlW6idqkLhwj2R86El/qgFAl8CwdoACgkQwj2R86El /qiVngf/c+ZYEytOSN7vwsPOVpLlgnj3ETWDdCWM6L7FNYB4qVzwXEcrXCg31qr8 xOkflYzIWNA+nB5uCBT+1bDdNmJfoHPORqO3VzN41NdMe/3nEZLdf7Akycnh0II1 7ztHDtPDeAwa3UlbnqeJeo3/jv+c1nXcXS5Xtyp1huntmxrXRor25LgQULRqk4bx HH7SKbSntnf9e+8+9pIMIlVtrrR2QzVTmvbatj7cmdjWev7S36V5w+COdqUnA7G9 gcb4V3xfj+/vMCitz7zSJWVjwW5Ihs1B3+jCJHcf09iP1qb73mto+UpK8vG8+ltf A2FrBAydokvNAkXZlowpJJQw/kFhpA== =hZsZ -----END PGP SIGNATURE----- --mlRMY68DA2QAMmYm2zqnAD6NEE3Vsmjkt--