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| author | Peter Maydell <peter.maydell@linaro.org> | 2020-09-16 14:47:50 +0100 |
|---|---|---|
| committer | Peter Maydell <peter.maydell@linaro.org> | 2020-09-16 14:47:50 +0100 |
| commit | 8ee612722dc08830761516e761dde934c3753a14 (patch) | |
| tree | 887764c495b002653f147a2ecc0dd7886479b165 | |
| parent | de39a045bd8d2b49e4f3d07976622c29d58e0bac (diff) | |
| parent | c418f935ac6aed9aa1dc0ceb4b19044a9b7b7968 (diff) | |
Merge remote-tracking branch 'remotes/cschoenebeck/tags/pull-9p-20200915' into staging
The intention of the following two patches is making users aware about
the negative file I/O performance impact when using a very low value
for 9P client parameter 'msize', which especially is the case if no
'msize' parameter was supplied by the user with a 9P Linux client at all.
All it does is logging a performance warning on host side (once) in
that case. By setting 'msize' on client side to any value larger than
8192 the performance warning will disappear.
See https://wiki.qemu.org/Documentation/9psetup#msize for details.
# gpg: Signature made Tue 15 Sep 2020 11:37:32 BST
# gpg: using RSA key 96D8D110CF7AF8084F88590134C2B58765A47395
# gpg: issuer "qemu_oss@crudebyte.com"
# gpg: Good signature from "Christian Schoenebeck <qemu_oss@crudebyte.com>" [unknown]
# gpg: WARNING: This key is not certified with a trusted signature!
# gpg: There is no indication that the signature belongs to the owner.
# Primary key fingerprint: ECAB 1A45 4014 1413 BA38 4926 30DB 47C3 A012 D5F4
# Subkey fingerprint: 96D8 D110 CF7A F808 4F88 5901 34C2 B587 65A4 7395
* remotes/cschoenebeck/tags/pull-9p-20200915:
9pfs: disable msize warning for synth driver
9pfs: log warning if msize <= 8192
Signed-off-by: Peter Maydell <peter.maydell@linaro.org>
| -rw-r--r-- | fsdev/file-op-9p.h | 4 | ||||
| -rw-r--r-- | hw/9pfs/9p-synth.c | 2 | ||||
| -rw-r--r-- | hw/9pfs/9p.c | 9 |
3 files changed, 15 insertions, 0 deletions
diff --git a/fsdev/file-op-9p.h b/fsdev/file-op-9p.h index f2f7772c86..d51cec2f3b 100644 --- a/fsdev/file-op-9p.h +++ b/fsdev/file-op-9p.h @@ -64,6 +64,10 @@ typedef struct ExtendedOps { */ #define V9FS_REMAP_INODES 0x00000200 #define V9FS_FORBID_MULTIDEVS 0x00000400 +/* + * Disables certain performance warnings from being logged on host side. + */ +#define V9FS_NO_PERF_WARN 0x00000800 #define V9FS_SEC_MASK 0x0000003C diff --git a/hw/9pfs/9p-synth.c b/hw/9pfs/9p-synth.c index 7eb210ffa8..cec8c0eefc 100644 --- a/hw/9pfs/9p-synth.c +++ b/hw/9pfs/9p-synth.c @@ -541,6 +541,8 @@ static int synth_init(FsContext *ctx, Error **errp) QLIST_INIT(&synth_root.child); qemu_mutex_init(&synth_mutex); + ctx->export_flags |= V9FS_NO_PERF_WARN; + /* Add "." and ".." entries for root */ v9fs_add_dir_node(&synth_root, synth_root.attr->mode, "..", synth_root.attr, synth_root.attr->inode); diff --git a/hw/9pfs/9p.c b/hw/9pfs/9p.c index 7bb994bbf2..741d222c3f 100644 --- a/hw/9pfs/9p.c +++ b/hw/9pfs/9p.c @@ -1353,6 +1353,15 @@ static void coroutine_fn v9fs_version(void *opaque) goto out; } + /* 8192 is the default msize of Linux clients */ + if (s->msize <= 8192 && !(s->ctx.export_flags & V9FS_NO_PERF_WARN)) { + warn_report_once( + "9p: degraded performance: a reasonable high msize should be " + "chosen on client/guest side (chosen msize is <= 8192). See " + "https://wiki.qemu.org/Documentation/9psetup#msize for details." + ); + } + marshal: err = pdu_marshal(pdu, offset, "ds", s->msize, &version); if (err < 0) { |