test-blkio-cgroup.sh
#!/bin/sh
mount /dev/sda7 /fs
echo 1 > /debug/tracing/events/writeback/balance_dirty_pages/enable
echo 1 > /debug/tracing/events/writeback/blkcg_dirty_ratelimit/enable
rmdir /cgroup/buffered_write
mkdir /cgroup/buffered_write
echo $$ > /cgroup/buffered_write/tasks
echo $((2<<20)) > /cgroup/buffered_write/blkio.throttle.buffered_write_bps
dd if=/dev/zero of=/fs/zero1 bs=1M count=100 &
dd if=/dev/zero of=/fs/zero2 bs=1M count=100 &
run 1:
104857600 bytes (105 MB) copied, 97.8103 s, 1.1 MB/s
104857600 bytes (105 MB) copied, 97.9835 s, 1.1 MB/s
run 2:
104857600 bytes (105 MB) copied, 98.5704 s, 1.1 MB/s
104857600 bytes (105 MB) copied, 98.6268 s, 1.1 MB/s
average bps: 100MiB / 98.248s = 1.02MiB/s
run 1 trace:
dd-3485 [000] .... 658.737063: blkcg_dirty_ratelimit: kbps=2048 dirty_rate=1932 dirty_ratelimit=1064 balanced_dirty_ratelimit=1088
dd-3485 [000] .... 658.976945: blkcg_dirty_ratelimit: kbps=2048 dirty_rate=2000 dirty_ratelimit=1076 balanced_dirty_ratelimit=1084
dd-3485 [000] .... 659.212830: blkcg_dirty_ratelimit: kbps=2048 dirty_rate=2440 dirty_ratelimit=992 balanced_dirty_ratelimit=900
dd-3485 [002] .... 659.470651: blkcg_dirty_ratelimit: kbps=2048 dirty_rate=1860 dirty_ratelimit=1044 balanced_dirty_ratelimit=1088
dd-3485 [002] .... 659.714535: blkcg_dirty_ratelimit: kbps=2048 dirty_rate=2360 dirty_ratelimit=976 balanced_dirty_ratelimit=904
dd-3485 [002] .... 659.976381: blkcg_dirty_ratelimit: kbps=2048 dirty_rate=1832 dirty_ratelimit=1036 balanced_dirty_ratelimit=1088
dd-3485 [000] .... 660.222254: blkcg_dirty_ratelimit: kbps=2048 dirty_rate=2340 dirty_ratelimit=972 balanced_dirty_ratelimit=904
dd-3485 [000] .... 660.484089: blkcg_dirty_ratelimit: kbps=2048 dirty_rate=1464 dirty_ratelimit=1164 balanced_dirty_ratelimit=1352
dd-3485 [000] .... 660.701984: blkcg_dirty_ratelimit: kbps=2048 dirty_rate=2640 dirty_ratelimit=1036 balanced_dirty_ratelimit=900
dd-3485 [000] .... 660.947856: blkcg_dirty_ratelimit: kbps=2048 dirty_rate=1948 dirty_ratelimit=1064 balanced_dirty_ratelimit=1084
dd-3485 [000] .... 661.187727: blkcg_dirty_ratelimit: kbps=2048 dirty_rate=2000 dirty_ratelimit=1076 balanced_dirty_ratelimit=1084
dd-3485 [000] .... 661.423572: blkcg_dirty_ratelimit: kbps=2048 dirty_rate=2440 dirty_ratelimit=992 balanced_dirty_ratelimit=900
dd-3485 [000] .... 661.681431: blkcg_dirty_ratelimit: kbps=2048 dirty_rate=2232 dirty_ratelimit=952 balanced_dirty_ratelimit=908
dd-3485 [002] .... 661.949290: blkcg_dirty_ratelimit: kbps=2048 dirty_rate=1432 dirty_ratelimit=1156 balanced_dirty_ratelimit=1356
dd-3485 [002] .... 662.169176: blkcg_dirty_ratelimit: kbps=2048 dirty_rate=2616 dirty_ratelimit=1032 balanced_dirty_ratelimit=900
dd-3485 [000] .... 662.417016: blkcg_dirty_ratelimit: kbps=2048 dirty_rate=2320 dirty_ratelimit=972 balanced_dirty_ratelimit=908
dd-3485 [000] .... 662.678903: blkcg_dirty_ratelimit: kbps=2048 dirty_rate=1464 dirty_ratelimit=1164 balanced_dirty_ratelimit=1352
dd-3485 [000] .... 662.896764: blkcg_dirty_ratelimit: kbps=2048 dirty_rate=2640 dirty_ratelimit=1036 balanced_dirty_ratelimit=900
dd-3485 [002] .... 663.142644: blkcg_dirty_ratelimit: kbps=2048 dirty_rate=2340 dirty_ratelimit=972 balanced_dirty_ratelimit=904
It looks good enough as a proposal. Could be made more accurate if necessary.
Signed-off-by: Wu Fengguang <fengguang.wu@xxxxxxxxx>
---
include/trace/events/writeback.h | 34 +++++++++++++++++++++++++++++
mm/page-writeback.c | 2 +
2 files changed, 36 insertions(+)
--- linux-next.orig/mm/page-writeback.c 2012-03-28 15:36:16.426093131 +0800
+++ linux-next/mm/page-writeback.c 2012-03-28 15:36:47.906092485 +0800
@@ -1163,6 +1163,8 @@ static void blkcg_update_dirty_ratelimit
ratelimit >>= PAGE_SHIFT;
blkcg->dirty_ratelimit = (blkcg->dirty_ratelimit + ratelimit) / 2 + 1;
+ trace_blkcg_dirty_ratelimit(bps, dirty_rate,
+ blkcg->dirty_ratelimit, ratelimit);
}
void blkcg_update_bandwidth(struct blkio_cgroup *blkcg)
--- linux-next.orig/include/trace/events/writeback.h 2012-03-28 14:25:16.026180561 +0800
+++ linux-next/include/trace/events/writeback.h 2012-03-28 15:36:47.906092485 +0800
@@ -249,6 +249,40 @@ TRACE_EVENT(global_dirty_state,
#define KBps(x) ((x) << (PAGE_SHIFT - 10))
+TRACE_EVENT(blkcg_dirty_ratelimit,
+
+ TP_PROTO(unsigned long bps,
+ unsigned long dirty_rate,
+ unsigned long dirty_ratelimit,
+ unsigned long balanced_dirty_ratelimit),
+
+ TP_ARGS(bps, dirty_rate, dirty_ratelimit, balanced_dirty_ratelimit),
+
+ TP_STRUCT__entry(
+ __field(unsigned long, kbps)
+ __field(unsigned long, dirty_rate)
+ __field(unsigned long, dirty_ratelimit)
+ __field(unsigned long, balanced_dirty_ratelimit)
+ ),
+
+ TP_fast_assign(
+ __entry->kbps = bps >> 10;
+ __entry->dirty_rate = KBps(dirty_rate);
+ __entry->dirty_ratelimit = KBps(dirty_ratelimit);
+ __entry->balanced_dirty_ratelimit =
+ KBps(balanced_dirty_ratelimit);
+ ),
+
+ TP_printk("kbps=%lu dirty_rate=%lu "
+ "dirty_ratelimit=%lu "
+ "balanced_dirty_ratelimit=%lu",
+ __entry->kbps,
+ __entry->dirty_rate,
+ __entry->dirty_ratelimit,
+ __entry->balanced_dirty_ratelimit
+ )
+);
+
TRACE_EVENT(bdi_dirty_ratelimit,
TP_PROTO(struct backing_dev_info *bdi,
--
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