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Pull request

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* Add 'drop-cache=on|off' option to file-posix.c.  The default is on.
    Disabling the option fixes a QEMU 3.0.0 performance regression when live
    migrating on the same host with cache.direct=off.
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Merge remote-tracking branch 'remotes/stefanha/tags/block-pull-request' into staging

Pull request

 * Add 'drop-cache=on|off' option to file-posix.c.  The default is on.
   Disabling the option fixes a QEMU 3.0.0 performance regression when live
   migrating on the same host with cache.direct=off.

# gpg: Signature made Wed 13 Mar 2019 11:07:48 GMT
# gpg:                using RSA key 9CA4ABB381AB73C8
# gpg: Good signature from "Stefan Hajnoczi <stefanha@redhat.com>" [full]
# gpg:                 aka "Stefan Hajnoczi <stefanha@gmail.com>" [full]
# Primary key fingerprint: 8695 A8BF D3F9 7CDA AC35  775A 9CA4 ABB3 81AB 73C8

* remotes/stefanha/tags/block-pull-request:
  file-posix: add drop-cache=on|off option

Signed-off-by: Peter Maydell <peter.maydell@linaro.org>
This commit is contained in:
Peter Maydell 2019-03-14 09:34:51 +00:00
commit dbbc277510
2 changed files with 22 additions and 0 deletions
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16
block/file-posix.c
View File

@ -157,6 +157,7 @@ typedef struct BDRVRawState {
bool page_cache_inconsistent:1;
bool has_fallocate;
bool needs_alignment;
bool drop_cache;
bool check_cache_dropped;
PRManager *pr_mgr;
@ -165,6 +166,7 @@ typedef struct BDRVRawState {
typedef struct BDRVRawReopenState {
int fd;
int open_flags;
bool drop_cache;
bool check_cache_dropped;
} BDRVRawReopenState;
@ -433,6 +435,13 @@ static QemuOptsList raw_runtime_opts = {
.type = QEMU_OPT_STRING,
.help = "id of persistent reservation manager object (default: none)",
},
#if defined(__linux__)
{
.name = "drop-cache",
.type = QEMU_OPT_BOOL,
.help = "invalidate page cache during live migration (default: on)",
},
#endif
{
.name = "x-check-cache-dropped",
.type = QEMU_OPT_BOOL,
@ -524,6 +533,7 @@ static int raw_open_common(BlockDriverState *bs, QDict *options,
}
}
s->drop_cache = qemu_opt_get_bool(opts, "drop-cache", true);
s->check_cache_dropped = qemu_opt_get_bool(opts, "x-check-cache-dropped",
false);
@ -933,6 +943,7 @@ static int raw_reopen_prepare(BDRVReopenState *state,
goto out;
}
rs->drop_cache = qemu_opt_get_bool_del(opts, "drop-cache", true);
rs->check_cache_dropped =
qemu_opt_get_bool_del(opts, "x-check-cache-dropped", false);
@ -977,6 +988,7 @@ static void raw_reopen_commit(BDRVReopenState *state)
BDRVRawReopenState *rs = state->opaque;
BDRVRawState *s = state->bs->opaque;
s->drop_cache = rs->drop_cache;
s->check_cache_dropped = rs->check_cache_dropped;
s->open_flags = rs->open_flags;
@ -2562,6 +2574,10 @@ static void coroutine_fn raw_co_invalidate_cache(BlockDriverState *bs,
return;
}
if (!s->drop_cache) {
return;
}
if (s->open_flags & O_DIRECT) {
return; /* No host kernel page cache */
}

6
qapi/block-core.json
View File

@ -2834,6 +2834,10 @@
# @locking: whether to enable file locking. If set to 'auto', only enable
# when Open File Descriptor (OFD) locking API is available
# (default: auto, since 2.10)
# @drop-cache: invalidate page cache during live migration. This prevents
# stale data on the migration destination with cache.direct=off.
# Currently only supported on Linux hosts.
# (default: on, since: 4.0)
# @x-check-cache-dropped: whether to check that page cache was dropped on live
# migration. May cause noticeable delays if the image
# file is large, do not use in production.
@ -2846,6 +2850,8 @@
'*pr-manager': 'str',
'*locking': 'OnOffAuto',
'*aio': 'BlockdevAioOptions',
'*drop-cache': {'type': 'bool',
'if': 'defined(CONFIG_LINUX)'},
'*x-check-cache-dropped': 'bool' } }
##