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Re: [Qemu-devel] [PATCH v3 0/2] The intro for QEMU disk I/O limits
From: |
Ryan Harper |
Subject: |
Re: [Qemu-devel] [PATCH v3 0/2] The intro for QEMU disk I/O limits |
Date: |
Sun, 31 Jul 2011 14:09:03 -0500 |
User-agent: |
Mutt/1.5.6+20040907i |
* Zhi Yong Wu <address@hidden> [2011-07-28 05:53]:
> The main goal of the patch is to effectively cap the disk I/O speed or counts
> of one single VM.It is only one draft, so it unavoidably has some drawbacks,
> if you catch them, please let me know.
>
> The patch will mainly introduce one block I/O throttling algorithm, one timer
> and one block queue for each I/O limits enabled drive.
>
> When a block request is coming in, the throttling algorithm will check if its
> I/O rate or counts exceed the limits; if yes, then it will enqueue to the
> block queue; The timer will periodically handle the I/O requests in it.
>
> Some available features follow as below:
> (1) global bps limit.
> -drive bps=xxx in bytes/s
> (2) only read bps limit
> -drive bps_rd=xxx in bytes/s
> (3) only write bps limit
> -drive bps_wr=xxx in bytes/s
> (4) global iops limit
> -drive iops=xxx in ios/s
> (5) only read iops limit
> -drive iops_rd=xxx in ios/s
> (6) only write iops limit
> -drive iops_wr=xxx in ios/s
> (7) the combination of some limits.
> -drive bps=xxx,iops=xxx
>
> Known Limitations:
> (1) #1 can not coexist with #2, #3
> (2) #4 can not coexist with #5, #6
> (3) When bps/iops limits are specified to a small value such as 511 bytes/s,
> this VM will hang up. We are considering how to handle this senario.
>
I don't yet have detailed info , but we've got a memory leak in the
code. After running the VM with a 1MB r and w limit for 8 hours or
so:
-drive bps_rd=$((1*1024*1024)),bps_wr=$((1*1024*1024))
I've got my system swapping with 43G resident in memory:
9913 root 20 0 87.3g 43g 548 D 9.6 34.5 44:00.87 qemu-system-x86
would be worth looking through the code and maybe a valgrind run to
catch the leak.
--
Ryan Harper
Software Engineer; Linux Technology Center
IBM Corp., Austin, Tx
address@hidden