| Message ID | 20200810101447.7380-3-den@openvz.org (mailing list archive) |
|---|---|
| State | New, archived |
| Headers | show |
| Series | block: add logging facility for long standing IO requests | expand |
On Monday, 2020-08-10 at 13:14:46 +03, Denis V. Lunev wrote: > + strftime(buf, sizeof(buf), "%m-%d %H:%M:%S", "%F %T" would include the year, which can be useful. > + localtime_r(&start_time_host_s, &t)); > + > + bs = blk_bs(blk_stats2blk(stats)); > + qemu_log("long %s[%ld] IO request: %d.03%d since %s.%03d bs: %s(%s, %s)\n", > + block_account_type(cookie->type), cookie->bytes, > + (int)(latency_ms / 1000), (int)(latency_ms % 1000), buf, > + (int)((cookie->start_time_ns / 1000000) % 1000), Is there a reason not to use %u rather than casting? dme.
On 8/20/20 11:03 AM, David Edmondson wrote: > On Monday, 2020-08-10 at 13:14:46 +03, Denis V. Lunev wrote: > >> + strftime(buf, sizeof(buf), "%m-%d %H:%M:%S", > "%F %T" would include the year, which can be useful. ok > >> + localtime_r(&start_time_host_s, &t)); >> + >> + bs = blk_bs(blk_stats2blk(stats)); >> + qemu_log("long %s[%ld] IO request: %d.03%d since %s.%03d bs: %s(%s, %s)\n", >> + block_account_type(cookie->type), cookie->bytes, >> + (int)(latency_ms / 1000), (int)(latency_ms % 1000), buf, >> + (int)((cookie->start_time_ns / 1000000) % 1000), > Is there a reason not to use %u rather than casting? no, we could use unsigned. Will resend shortly.
On 10.08.20 12:14, Denis V. Lunev wrote: > There are severe delays with IO requests processing if QEMU is running in > virtual machine or over software defined storage. Such delays potentially > results in unpredictable guest behavior. For example, guests over IDE or > SATA drive could remount filesystem read-only if write is performed > longer than 10 seconds. > > Such reports are very complex to process. Some good starting point for this > seems quite reasonable. This patch provides one. It adds logging of such > potentially dangerous long IO operations. > > Signed-off-by: Denis V. Lunev <den@openvz.org> > Reviewed-by: Vladimir Sementsov-Ogievskiy <vsementsov@virtuozzo.com> > CC: Stefan Hajnoczi <stefanha@redhat.com> > CC: Kevin Wolf <kwolf@redhat.com> > CC: Max Reitz <mreitz@redhat.com> > --- > block/accounting.c | 59 +++++++++++++++++++++++++++++++++++++- > blockdev.c | 7 ++++- > include/block/accounting.h | 5 +++- > 3 files changed, 68 insertions(+), 3 deletions(-) > > diff --git a/block/accounting.c b/block/accounting.c > index 8d41c8a83a..24f48c84b8 100644 > --- a/block/accounting.c > +++ b/block/accounting.c [...] > @@ -182,6 +185,58 @@ void block_latency_histograms_clear(BlockAcctStats *stats) > } > } > > +static const char *block_account_type(enum BlockAcctType type) > +{ > + switch (type) { > + case BLOCK_ACCT_READ: > + return "READ"; > + case BLOCK_ACCT_WRITE: > + return "WRITE"; > + case BLOCK_ACCT_FLUSH: > + return "DISCARD"; > + case BLOCK_ACCT_UNMAP: > + return "TRUNCATE"; I don’t understand how FLUSH translates to DISCARD, and UNMAP to TRUNCATE. > + case BLOCK_ACCT_NONE: > + return "NONE"; > + case BLOCK_MAX_IOTYPE: > + break; > + } > + return "UNKNOWN"; > +} > + > +static void block_acct_report_long(BlockAcctStats *stats, > + BlockAcctCookie *cookie, int64_t latency_ns) > +{ > + unsigned latency_ms = latency_ns / SCALE_MS; > + int64_t start_time_host_s; > + char buf[64]; > + struct tm t; > + BlockDriverState *bs; > + > + if (cookie->type == BLOCK_ACCT_NONE) { > + return; > + } > + if (stats->latency_log_threshold_ms == 0) { > + return; > + } > + if (latency_ms < stats->latency_log_threshold_ms) { > + return; > + } > + > + start_time_host_s = cookie->start_time_ns / NANOSECONDS_PER_SECOND; > + strftime(buf, sizeof(buf), "%m-%d %H:%M:%S", > + localtime_r(&start_time_host_s, &t)); > + > + bs = blk_bs(blk_stats2blk(stats)); > + qemu_log("long %s[%ld] IO request: %d.03%d since %s.%03d bs: %s(%s, %s)\n", > + block_account_type(cookie->type), cookie->bytes, > + (int)(latency_ms / 1000), (int)(latency_ms % 1000), buf, Why not just latency_ms * .001f and %.3f? > + (int)((cookie->start_time_ns / 1000000) % 1000), s/1000000/SCALE_MS/? (But I’m not sure whether that’s what the SCALE_?S are for.) > + bs == NULL ? "unknown" : bdrv_get_node_name(bs), > + bs == NULL ? "unknown" : bdrv_get_format_name(bs), > + bs == NULL ? "unknown" : bs->filename); Now that I’m writing this response already, I wonder whether a QMP event wouldn’t be nice. (But considering that accounting apparently just doesn’t with -blockdev, I suppose that’s not that big of a worry.) > +} > + > static void block_account_one_io(BlockAcctStats *stats, BlockAcctCookie *cookie, > bool failed) > { [...] > diff --git a/blockdev.c b/blockdev.c > index 3848a9c8ab..66158d1292 100644 > --- a/blockdev.c > +++ b/blockdev.c > @@ -622,7 +622,8 @@ static BlockBackend *blockdev_init(const char *file, QDict *bs_opts, > > bs->detect_zeroes = detect_zeroes; > > - block_acct_setup(blk_get_stats(blk), account_invalid, account_failed); > + block_acct_setup(blk_get_stats(blk), account_invalid, account_failed, > + qemu_opt_get_number(opts, "latency-log-threshold", 0)); latency_log_threshold_ms is an unsigned int and so this will silently overflow for values >= 2^32. (Or for user-specified values < 0, which are wrapped around.) > > if (!parse_stats_intervals(blk_get_stats(blk), interval_list, errp)) { > blk_unref(blk); > @@ -3727,6 +3728,10 @@ QemuOptsList qemu_common_drive_opts = { > .type = QEMU_OPT_BOOL, > .help = "whether to account for failed I/O operations " > "in the statistics", > + },{ > + .name = "latency-log-threshold", > + .type = QEMU_OPT_NUMBER, > + .help = "threshold for long I/O report (disabled if <=0), in ms", Because of that overflow, negative values will not necessarily disable reporting, because truncating them to 32 bit may make them small absolute values again. In any case, I’d just say “disabled if 0”, and not mention anything about <0. Max
On 9/17/20 4:56 PM, Max Reitz wrote: > On 10.08.20 12:14, Denis V. Lunev wrote: >> There are severe delays with IO requests processing if QEMU is running in >> virtual machine or over software defined storage. Such delays potentially >> results in unpredictable guest behavior. For example, guests over IDE or >> SATA drive could remount filesystem read-only if write is performed >> longer than 10 seconds. >> >> Such reports are very complex to process. Some good starting point for this >> seems quite reasonable. This patch provides one. It adds logging of such >> potentially dangerous long IO operations. >> >> Signed-off-by: Denis V. Lunev <den@openvz.org> >> Reviewed-by: Vladimir Sementsov-Ogievskiy <vsementsov@virtuozzo.com> >> CC: Stefan Hajnoczi <stefanha@redhat.com> >> CC: Kevin Wolf <kwolf@redhat.com> >> CC: Max Reitz <mreitz@redhat.com> >> --- >> block/accounting.c | 59 +++++++++++++++++++++++++++++++++++++- >> blockdev.c | 7 ++++- >> include/block/accounting.h | 5 +++- >> 3 files changed, 68 insertions(+), 3 deletions(-) >> >> diff --git a/block/accounting.c b/block/accounting.c >> index 8d41c8a83a..24f48c84b8 100644 >> --- a/block/accounting.c >> +++ b/block/accounting.c > [...] > >> @@ -182,6 +185,58 @@ void block_latency_histograms_clear(BlockAcctStats *stats) >> } >> } >> >> +static const char *block_account_type(enum BlockAcctType type) >> +{ >> + switch (type) { >> + case BLOCK_ACCT_READ: >> + return "READ"; >> + case BLOCK_ACCT_WRITE: >> + return "WRITE"; >> + case BLOCK_ACCT_FLUSH: >> + return "DISCARD"; >> + case BLOCK_ACCT_UNMAP: >> + return "TRUNCATE"; > I don’t understand how FLUSH translates to DISCARD, and UNMAP to TRUNCATE. > Ha, seems I have made copy/pasted and missed this. Nice catch. >> + case BLOCK_ACCT_NONE: >> + return "NONE"; >> + case BLOCK_MAX_IOTYPE: >> + break; >> + } >> + return "UNKNOWN"; >> +} >> + >> +static void block_acct_report_long(BlockAcctStats *stats, >> + BlockAcctCookie *cookie, int64_t latency_ns) >> +{ >> + unsigned latency_ms = latency_ns / SCALE_MS; >> + int64_t start_time_host_s; >> + char buf[64]; >> + struct tm t; >> + BlockDriverState *bs; >> + >> + if (cookie->type == BLOCK_ACCT_NONE) { >> + return; >> + } >> + if (stats->latency_log_threshold_ms == 0) { >> + return; >> + } >> + if (latency_ms < stats->latency_log_threshold_ms) { >> + return; >> + } >> + >> + start_time_host_s = cookie->start_time_ns / NANOSECONDS_PER_SECOND; >> + strftime(buf, sizeof(buf), "%m-%d %H:%M:%S", >> + localtime_r(&start_time_host_s, &t)); >> + >> + bs = blk_bs(blk_stats2blk(stats)); >> + qemu_log("long %s[%ld] IO request: %d.03%d since %s.%03d bs: %s(%s, %s)\n", >> + block_account_type(cookie->type), cookie->bytes, >> + (int)(latency_ms / 1000), (int)(latency_ms % 1000), buf, > Why not just latency_ms * .001f and %.3f? I personally dislike floating point, this leads to a bit strange output. > >> + (int)((cookie->start_time_ns / 1000000) % 1000), > s/1000000/SCALE_MS/? (But I’m not sure whether that’s what the SCALE_?S > are for.) yes, you right. >> + bs == NULL ? "unknown" : bdrv_get_node_name(bs), >> + bs == NULL ? "unknown" : bdrv_get_format_name(bs), >> + bs == NULL ? "unknown" : bs->filename); > Now that I’m writing this response already, I wonder whether a QMP event > wouldn’t be nice. (But considering that accounting apparently just > doesn’t with -blockdev, I suppose that’s not that big of a worry.) may be. Why not? Though there is some note. Usually after the stall there is a bunch of requests completed at the same time once the storage is unfrozen, thus some aggregation would be required. I think that this should be made separately. >> +} >> + >> static void block_account_one_io(BlockAcctStats *stats, BlockAcctCookie *cookie, >> bool failed) >> { > [...] > >> diff --git a/blockdev.c b/blockdev.c >> index 3848a9c8ab..66158d1292 100644 >> --- a/blockdev.c >> +++ b/blockdev.c >> @@ -622,7 +622,8 @@ static BlockBackend *blockdev_init(const char *file, QDict *bs_opts, >> >> bs->detect_zeroes = detect_zeroes; >> >> - block_acct_setup(blk_get_stats(blk), account_invalid, account_failed); >> + block_acct_setup(blk_get_stats(blk), account_invalid, account_failed, >> + qemu_opt_get_number(opts, "latency-log-threshold", 0)); > latency_log_threshold_ms is an unsigned int and so this will silently > overflow for values >= 2^32. > > (Or for user-specified values < 0, which are wrapped around.) > >> >> if (!parse_stats_intervals(blk_get_stats(blk), interval_list, errp)) { >> blk_unref(blk); >> @@ -3727,6 +3728,10 @@ QemuOptsList qemu_common_drive_opts = { >> .type = QEMU_OPT_BOOL, >> .help = "whether to account for failed I/O operations " >> "in the statistics", >> + },{ >> + .name = "latency-log-threshold", >> + .type = QEMU_OPT_NUMBER, >> + .help = "threshold for long I/O report (disabled if <=0), in ms", > Because of that overflow, negative values will not necessarily disable > reporting, because truncating them to 32 bit may make them small > absolute values again. > > In any case, I’d just say “disabled if 0”, and not mention anything > about <0. will do. Thanks for review! Den
diff --git a/block/accounting.c b/block/accounting.c index 8d41c8a83a..24f48c84b8 100644 --- a/block/accounting.c +++ b/block/accounting.c @@ -27,7 +27,9 @@ #include "block/accounting.h" #include "block/block_int.h" #include "qemu/timer.h" +#include "qemu/log.h" #include "sysemu/qtest.h" +#include "sysemu/block-backend.h" static QEMUClockType clock_type = QEMU_CLOCK_REALTIME; static const int qtest_latency_ns = NANOSECONDS_PER_SECOND / 1000; @@ -41,10 +43,11 @@ void block_acct_init(BlockAcctStats *stats) } void block_acct_setup(BlockAcctStats *stats, bool account_invalid, - bool account_failed) + bool account_failed, unsigned latency_log_threshold_ms) { stats->account_invalid = account_invalid; stats->account_failed = account_failed; + stats->latency_log_threshold_ms = latency_log_threshold_ms; } void block_acct_cleanup(BlockAcctStats *stats) @@ -182,6 +185,58 @@ void block_latency_histograms_clear(BlockAcctStats *stats) } } +static const char *block_account_type(enum BlockAcctType type) +{ + switch (type) { + case BLOCK_ACCT_READ: + return "READ"; + case BLOCK_ACCT_WRITE: + return "WRITE"; + case BLOCK_ACCT_FLUSH: + return "DISCARD"; + case BLOCK_ACCT_UNMAP: + return "TRUNCATE"; + case BLOCK_ACCT_NONE: + return "NONE"; + case BLOCK_MAX_IOTYPE: + break; + } + return "UNKNOWN"; +} + +static void block_acct_report_long(BlockAcctStats *stats, + BlockAcctCookie *cookie, int64_t latency_ns) +{ + unsigned latency_ms = latency_ns / SCALE_MS; + int64_t start_time_host_s; + char buf[64]; + struct tm t; + BlockDriverState *bs; + + if (cookie->type == BLOCK_ACCT_NONE) { + return; + } + if (stats->latency_log_threshold_ms == 0) { + return; + } + if (latency_ms < stats->latency_log_threshold_ms) { + return; + } + + start_time_host_s = cookie->start_time_ns / NANOSECONDS_PER_SECOND; + strftime(buf, sizeof(buf), "%m-%d %H:%M:%S", + localtime_r(&start_time_host_s, &t)); + + bs = blk_bs(blk_stats2blk(stats)); + qemu_log("long %s[%ld] IO request: %d.03%d since %s.%03d bs: %s(%s, %s)\n", + block_account_type(cookie->type), cookie->bytes, + (int)(latency_ms / 1000), (int)(latency_ms % 1000), buf, + (int)((cookie->start_time_ns / 1000000) % 1000), + bs == NULL ? "unknown" : bdrv_get_node_name(bs), + bs == NULL ? "unknown" : bdrv_get_format_name(bs), + bs == NULL ? "unknown" : bs->filename); +} + static void block_account_one_io(BlockAcctStats *stats, BlockAcctCookie *cookie, bool failed) { @@ -222,6 +277,8 @@ static void block_account_one_io(BlockAcctStats *stats, BlockAcctCookie *cookie, qemu_mutex_unlock(&stats->lock); + block_acct_report_long(stats, cookie, latency_ns); + cookie->type = BLOCK_ACCT_NONE; } diff --git a/blockdev.c b/blockdev.c index 3848a9c8ab..66158d1292 100644 --- a/blockdev.c +++ b/blockdev.c @@ -622,7 +622,8 @@ static BlockBackend *blockdev_init(const char *file, QDict *bs_opts, bs->detect_zeroes = detect_zeroes; - block_acct_setup(blk_get_stats(blk), account_invalid, account_failed); + block_acct_setup(blk_get_stats(blk), account_invalid, account_failed, + qemu_opt_get_number(opts, "latency-log-threshold", 0)); if (!parse_stats_intervals(blk_get_stats(blk), interval_list, errp)) { blk_unref(blk); @@ -3727,6 +3728,10 @@ QemuOptsList qemu_common_drive_opts = { .type = QEMU_OPT_BOOL, .help = "whether to account for failed I/O operations " "in the statistics", + },{ + .name = "latency-log-threshold", + .type = QEMU_OPT_NUMBER, + .help = "threshold for long I/O report (disabled if <=0), in ms", }, { /* end of list */ } }, diff --git a/include/block/accounting.h b/include/block/accounting.h index 878b4c3581..c3ea25f9aa 100644 --- a/include/block/accounting.h +++ b/include/block/accounting.h @@ -91,6 +91,9 @@ struct BlockAcctStats { bool account_invalid; bool account_failed; BlockLatencyHistogram latency_histogram[BLOCK_MAX_IOTYPE]; + + /* Threshold for long I/O detection, ms */ + unsigned latency_log_threshold_ms; }; typedef struct BlockAcctCookie { @@ -101,7 +104,7 @@ typedef struct BlockAcctCookie { void block_acct_init(BlockAcctStats *stats); void block_acct_setup(BlockAcctStats *stats, bool account_invalid, - bool account_failed); + bool account_failed, unsigned latency_log_threshold_ms); void block_acct_cleanup(BlockAcctStats *stats); void block_acct_add_interval(BlockAcctStats *stats, unsigned interval_length); BlockAcctTimedStats *block_acct_interval_next(BlockAcctStats *stats,