Messages in this thread | | | Date | Wed, 24 Aug 2011 08:06:12 +0200 | From | Stefan Priebe - Profihost AG <> | Subject | slow performance on disk/network i/o full speed after drop_caches |
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Dear list,
i hope this is the correct list to write to if it would be nice to give me a hint where i can ask.
Kernel: 2.6.38
I'm seeing some strange problems on some of our servers after upgrading to 2.6.38.
I'm copying a 1GB file via scp from Machine A to Machine B. When B is freshly booted the file transfer is done with about 80 to 85 Mb/s. I can repeat that various times to performance degrease.
Then after some days copying is only done with about 900kb/s up to 3Mb/s going up and down while transfering the file.
When i then do drop_caches it works again on 80Mb/s.
sync && echo 3 >/proc/sys/vm/drop_caches && sleep 2 && echo 0 >/proc/sys/vm/drop_caches
Attached is also an output of meminfo before and after drop_caches.
What's going on here? MemFree is pretty high.
Please CC me i'm not on list.
Greets Stefan
# before drop_caches
# cat /proc/meminfo MemTotal: 8185544 kB MemFree: 6670292 kB Buffers: 105164 kB Cached: 166672 kB SwapCached: 0 kB Active: 728308 kB Inactive: 567428 kB Active(anon): 639204 kB Inactive(anon): 394932 kB Active(file): 89104 kB Inactive(file): 172496 kB Unevictable: 2976 kB Mlocked: 2992 kB SwapTotal: 1464316 kB SwapFree: 1464316 kB Dirty: 52 kB Writeback: 0 kB AnonPages: 1026920 kB Mapped: 54208 kB Shmem: 8380 kB Slab: 80724 kB SReclaimable: 22844 kB SUnreclaim: 57880 kB KernelStack: 2872 kB PageTables: 35448 kB NFS_Unstable: 0 kB Bounce: 0 kB WritebackTmp: 0 kB CommitLimit: 5557088 kB Committed_AS: 6187972 kB VmallocTotal: 34359738367 kB VmallocUsed: 292360 kB VmallocChunk: 34359425327 kB HardwareCorrupted: 0 kB DirectMap4k: 5632 kB DirectMap2M: 2082816 kB DirectMap1G: 6291456 kB
# cat /proc/meminfo MemTotal: 8185544 kB MemFree: 6888060 kB Buffers: 372 kB Cached: 61492 kB SwapCached: 0 kB Active: 659156 kB Inactive: 426664 kB Active(anon): 638892 kB Inactive(anon): 395200 kB Active(file): 20264 kB Inactive(file): 31464 kB Unevictable: 2976 kB Mlocked: 2992 kB SwapTotal: 1464316 kB SwapFree: 1464316 kB Dirty: 0 kB Writeback: 0 kB AnonPages: 1026952 kB Mapped: 54236 kB Shmem: 8316 kB Slab: 70616 kB SReclaimable: 12264 kB SUnreclaim: 58352 kB KernelStack: 2864 kB PageTables: 35448 kB NFS_Unstable: 0 kB Bounce: 0 kB WritebackTmp: 0 kB CommitLimit: 5557088 kB Committed_AS: 6187932 kB VmallocTotal: 34359738367 kB VmallocUsed: 292360 kB VmallocChunk: 34359425327 kB HardwareCorrupted: 0 kB DirectMap4k: 5632 kB DirectMap2M: 2082816 kB DirectMap1G: 6291456 kB
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