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X-Received-From: 207.171.184.29 Subject: [Qemu-devel] [PATCH] blkdebug: Add support for latency rules X-BeenThere: qemu-devel@nongnu.org X-Mailman-Version: 2.1.21 List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , From: Marc Olson via Qemu-devel Reply-To: Marc Olson Cc: Kevin Wolf , Marc Olson , qemu-devel@nongnu.org, qemu-block@nongnu.org, Max Reitz Errors-To: qemu-devel-bounces+importer=patchew.org@nongnu.org Sender: "Qemu-devel" X-ZohoMail-DKIM: fail (Header signature does not verify) X-ZohoMail: RDKM_2 RSF_0 Z_629925259 SPT_0 Content-Transfer-Encoding: quoted-printable MIME-Version: 1.0 Content-Type: text/plain; charset="utf-8" Allow rules to be created to inject latency into I/O operations. Signed-off-by: Marc Olson --- block/blkdebug.c | 101 ++++++++++++++++++++++++++++++++++++++------= ---- docs/devel/blkdebug.txt | 30 ++++++++++---- 2 files changed, 103 insertions(+), 28 deletions(-) diff --git a/block/blkdebug.c b/block/blkdebug.c index e216699..762e438 100644 --- a/block/blkdebug.c +++ b/block/blkdebug.c @@ -65,6 +65,7 @@ typedef struct BlkdebugSuspendedReq { =20 enum { ACTION_INJECT_ERROR, + ACTION_DELAY, ACTION_SET_STATE, ACTION_SUSPEND, }; @@ -73,14 +74,17 @@ typedef struct BlkdebugRule { BlkdebugEvent event; int action; int state; + int once; + int64_t offset; union { struct { int error; int immediately; - int once; - int64_t offset; } inject; struct { + int64_t latency; + } delay; + struct { int new_state; } set_state; struct { @@ -123,6 +127,33 @@ static QemuOptsList inject_error_opts =3D { }, }; =20 +static QemuOptsList delay_opts =3D { + .name =3D "delay", + .head =3D QTAILQ_HEAD_INITIALIZER(delay_opts.head), + .desc =3D { + { + .name =3D "event", + }, + { + .name =3D "state", + .type =3D QEMU_OPT_NUMBER, + }, + { + .name =3D "latency", + .type =3D QEMU_OPT_NUMBER, + }, + { + .name =3D "sector", + .type =3D QEMU_OPT_NUMBER, + }, + { + .name =3D "once", + .type =3D QEMU_OPT_BOOL, + }, + { /* end of list */ } + }, +}; + static QemuOptsList set_state_opts =3D { .name =3D "set-state", .head =3D QTAILQ_HEAD_INITIALIZER(set_state_opts.head), @@ -145,6 +176,7 @@ static QemuOptsList set_state_opts =3D { =20 static QemuOptsList *config_groups[] =3D { &inject_error_opts, + &delay_opts, &set_state_opts, NULL }; @@ -182,16 +214,21 @@ static int add_rule(void *opaque, QemuOpts *opts, Err= or **errp) .state =3D qemu_opt_get_number(opts, "state", 0), }; =20 + rule->once =3D qemu_opt_get_bool(opts, "once", 0); + sector =3D qemu_opt_get_number(opts, "sector", -1); + rule->offset =3D sector =3D=3D -1 ? -1 : sector * BDRV_SECTOR_SIZE; + /* Parse action-specific options */ switch (d->action) { case ACTION_INJECT_ERROR: rule->options.inject.error =3D qemu_opt_get_number(opts, "errno", = EIO); - rule->options.inject.once =3D qemu_opt_get_bool(opts, "once", 0); rule->options.inject.immediately =3D qemu_opt_get_bool(opts, "immediately", 0); - sector =3D qemu_opt_get_number(opts, "sector", -1); - rule->options.inject.offset =3D - sector =3D=3D -1 ? -1 : sector * BDRV_SECTOR_SIZE; + break; + + case ACTION_DELAY: + rule->options.delay.latency =3D + qemu_opt_get_number(opts, "latency", 100) * SCALE_US; break; =20 case ACTION_SET_STATE: @@ -264,6 +301,14 @@ static int read_config(BDRVBlkdebugState *s, const cha= r *filename, goto fail; } =20 + d.action =3D ACTION_DELAY; + qemu_opts_foreach(&delay_opts, add_rule, &d, &local_err); + if (local_err) { + error_propagate(errp, local_err); + ret =3D -EINVAL; + goto fail; + } + d.action =3D ACTION_SET_STATE; qemu_opts_foreach(&set_state_opts, add_rule, &d, &local_err); if (local_err) { @@ -275,6 +320,7 @@ static int read_config(BDRVBlkdebugState *s, const char= *filename, ret =3D 0; fail: qemu_opts_reset(&inject_error_opts); + qemu_opts_reset(&delay_opts); qemu_opts_reset(&set_state_opts); if (f) { fclose(f); @@ -475,36 +521,50 @@ static int rule_check(BlockDriverState *bs, uint64_t = offset, uint64_t bytes) BlkdebugRule *rule =3D NULL; int error; bool immediately; + int ret =3D 0; =20 QSIMPLEQ_FOREACH(rule, &s->active_rules, active_next) { - uint64_t inject_offset =3D rule->options.inject.offset; - - if (inject_offset =3D=3D -1 || - (bytes && inject_offset >=3D offset && - inject_offset < offset + bytes)) + if (rule->offset =3D=3D -1 || + (bytes && rule->offset >=3D offset && + rule->offset < offset + bytes)) { break; } } =20 - if (!rule || !rule->options.inject.error) { + if (!rule || + (rule->action =3D=3D ACTION_INJECT_ERROR && !rule->options.inject.= error) || + (rule->action =3D=3D ACTION_DELAY && !rule->options.delay.latency)= ) { return 0; } =20 - immediately =3D rule->options.inject.immediately; - error =3D rule->options.inject.error; - - if (rule->options.inject.once) { + if (rule->once) { QSIMPLEQ_REMOVE(&s->active_rules, rule, BlkdebugRule, active_next); remove_rule(rule); } =20 - if (!immediately) { - aio_co_schedule(qemu_get_current_aio_context(), qemu_coroutine_sel= f()); - qemu_coroutine_yield(); + switch (rule->action) { + case ACTION_INJECT_ERROR: + immediately =3D rule->options.inject.immediately; + error =3D rule->options.inject.error; + + if (!immediately) { + aio_co_schedule(qemu_get_current_aio_context(), + qemu_coroutine_self()); + qemu_coroutine_yield(); + } + + ret =3D -error; + break; + + case ACTION_DELAY: + if (rule->options.delay.latency) { + qemu_co_sleep_ns(QEMU_CLOCK_REALTIME, rule->options.delay.late= ncy); + } + break; } =20 - return -error; + return ret; } =20 static int coroutine_fn @@ -691,6 +751,7 @@ static bool process_rule(BlockDriverState *bs, struct B= lkdebugRule *rule, /* Take the action */ switch (rule->action) { case ACTION_INJECT_ERROR: + case ACTION_DELAY: if (!injected) { QSIMPLEQ_INIT(&s->active_rules); injected =3D true; diff --git a/docs/devel/blkdebug.txt b/docs/devel/blkdebug.txt index 43d8e8f..1befcf8 100644 --- a/docs/devel/blkdebug.txt +++ b/docs/devel/blkdebug.txt @@ -24,7 +24,7 @@ This way, all error paths can be tested to make sure they= are correct. Rules ----- The blkdebug block driver takes a list of "rules" that tell the error inje= ction -engine when to fail an I/O request. +engine when to fail (inject-error) or add latency to (delay) an I/O reques= t. =20 Each I/O request is evaluated against the rules. If a rule matches the re= quest then its "action" is executed. @@ -33,17 +33,25 @@ Rules can be placed in a configuration file; the config= uration file follows the same .ini-like format used by QEMU's -readconfig option, and each section of the file represents a rule. =20 -The following configuration file defines a single rule: +The following configuration file defines multiple rules: =20 $ cat blkdebug.conf [inject-error] event =3D "read_aio" errno =3D "28" =20 -This rule fails all aio read requests with ENOSPC (28). Note that the err= no -value depends on the host. On Linux, see + [delay] + event =3D "read_aio" + sector =3D "2048" + latency =3D "500000" + +The error rule fails all aio read requests with ENOSPC (28). Note that the +errno value depends on the host. On Linux, see /usr/include/asm-generic/errno-base.h for errno values. =20 +The delay rule adds 500 ms of latency to a read I/O request containing sec= tor +2048. + Invoke QEMU as follows: =20 $ qemu-system-x86_64 @@ -60,21 +68,27 @@ Rules support the following attributes: rule to match. See the "State transitions" section for informat= ion on states. =20 - errno - the numeric errno value to return when a request matches this ru= le. - The errno values depend on the host since the numeric values are= not - standarized in the POSIX specification. - sector - (optional) a sector number that the request must overlap in ord= er to match this rule =20 once - (optional, default "off") only execute this action on the first matching request =20 +Error injection rules support the following attributes: + + errno - the numeric errno value to return when a request matches this ru= le. + The errno values depend on the host since the numeric values are= not + standarized in the POSIX specification. + immediately - (optional, default "off") return a NULL BlockAIOCB pointer and fail without an errno instead. This exercises the code path where BlockAIOCB fails and the caller's BlockCompletionFunc is not invoked. =20 +Delay rules support the following attribute: + + latency - the delay to add to an I/O request, in microseconds. + Events ------ Block drivers provide information about the type of I/O request they are a= bout --=20 2.7.4