Date: Tue, 26 May 2026 21:23:02 +0000 From: Alex Richardson <arichardson@FreeBSD.org> To: src-committers@FreeBSD.org, dev-commits-src-all@FreeBSD.org, dev-commits-src-main@FreeBSD.org Subject: git: 882181b1ae4c - main - p9fs: Implement msize mount option and bump default to 128 KiB Message-ID: <6a160f36.22e4e.1d353044@gitrepo.freebsd.org>
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The branch main has been updated by arichardson: URL: https://cgit.FreeBSD.org/src/commit/?id=882181b1ae4c78b4f191fdb7cf6fe1b6ff83c9ff commit 882181b1ae4c78b4f191fdb7cf6fe1b6ff83c9ff Author: Alex Richardson <arichardson@FreeBSD.org> AuthorDate: 2026-05-26 19:38:18 +0000 Commit: Alex Richardson <arichardson@FreeBSD.org> CommitDate: 2026-05-26 19:38:18 +0000 p9fs: Implement msize mount option and bump default to 128 KiB QEMU warns when msize is <= 8192 due to degraded performance. This change bumps our default msize to 128 KiB, matching the Linux Kernel v5.15 and newer default. Linux supports even larger values, but 128 KiB is a sensible default. We also add a new 'msize' mount option to allow users to override this value, and we validate it against our maximum supported MTU (currently fixed by the UMA zone size). Reviewed by: markj MFC after: 1 week Differential Revision: https://reviews.freebsd.org/D56496 --- sys/fs/p9fs/p9_client.c | 9 ++++++++- sys/fs/p9fs/p9_client.h | 7 +++++-- sys/fs/p9fs/p9fs_vfsops.c | 2 +- 3 files changed, 14 insertions(+), 4 deletions(-) diff --git a/sys/fs/p9fs/p9_client.c b/sys/fs/p9fs/p9_client.c index 27a6c1eb366d..d3be87ee1645 100644 --- a/sys/fs/p9fs/p9_client.c +++ b/sys/fs/p9fs/p9_client.c @@ -95,7 +95,14 @@ p9_parse_opts(struct mount *mp, struct p9_client *clnt) /* These are defaults for now */ clnt->proto_version = p9_proto_2000L; - clnt->msize = 8192; + clnt->msize = P9FS_MTU; + + vfs_scanopt(mp->mnt_optnew, "msize", "%u", &clnt->msize); + if (clnt->msize > P9FS_MTU) { + vfs_mount_error(mp, "msize %u is greater than max allowed %u", + clnt->msize, P9FS_MTU); + return (EINVAL); + } /* Get the default trans callback */ clnt->ops = p9_get_trans_by_name(trans); diff --git a/sys/fs/p9fs/p9_client.h b/sys/fs/p9fs/p9_client.h index 5db46d97c704..e5167f9a0f58 100644 --- a/sys/fs/p9fs/p9_client.h +++ b/sys/fs/p9fs/p9_client.h @@ -65,8 +65,11 @@ enum transport_status { P9FS_DISCONNECT, /* transport has been dosconnected */ }; -/* This is set by QEMU so we will oblige */ -#define P9FS_MTU 8192 +/* + * This matches the Linux 5.15 and newer default. + * Note: Linux allows larger msize values than this. + */ +#define P9FS_MTU 131072 /* * Even though we have a 8k buffer, Qemu is typically doing 8168 diff --git a/sys/fs/p9fs/p9fs_vfsops.c b/sys/fs/p9fs/p9fs_vfsops.c index a0f0a5a4e494..fe8c1b5ded31 100644 --- a/sys/fs/p9fs/p9fs_vfsops.c +++ b/sys/fs/p9fs/p9fs_vfsops.c @@ -59,7 +59,7 @@ extern struct vop_vector p9fs_vnops; /* option parsing */ static const char *p9fs_opts[] = { - "from", "trans", "access", NULL + "from", "trans", "access", "msize", NULL }; /* Dispose p9fs node, freeing it to the UMA zone */home | help
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