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Re: [Qemu-block] [PATCH v12 0/9] Take the image size into account when a
From: |
Kevin Wolf |
Subject: |
Re: [Qemu-block] [PATCH v12 0/9] Take the image size into account when allocating the L2 cache |
Date: |
Thu, 27 Sep 2018 17:23:10 +0200 |
User-agent: |
Mutt/1.9.1 (2017-09-22) |
Am 26.09.2018 um 18:04 hat Leonid Bloch geschrieben:
> This series makes the qcow2 L2 cache assignment aware of the image size,
> with the intention for it to cover the entire image. The importance of
> this change is in noticeable performance improvement, especially with
> heavy random I/O. The memory overhead is not big in most cases, as only
> 1 MB of cache for every 8 GB of image size is used. For cases with very
> large images and/or small cluster sizes, or systems with limited RAM
> resources, there is an upper limit on the default L2 cache: 32 MB for
> Linux systems, and 8 MB for non-Linux systems (the difference is caused
> by the fact that it is currently impossible to perform scheduled cache
> cleaning on non-Linux systems). To modify this upper limit one can use
> the already existing 'l2-cache-size' and 'cache-size' options. Moreover,
> this fixes the behavior of 'l2-cache-size', as it was documented as the
> *maximum* L2 cache size, but in practice behaved as the absolute size.
>
> To compensate the memory overhead which may (but not necesarily will) be
> increased following this behavior, the default cache-clean-interval is set
> to 10 minutes by default (was disabled by default before).
>
> The L2 cache is also resized accordingly, by default, if the image is
> resized.
>
> Additionally, few minor changes are made (refactoring and documentation
> fixes).
Thanks, applied to the block branch.
Kevin
- [Qemu-block] [PATCH v12 2/9] include: Add a lookup table of sizes, (continued)
- [Qemu-block] [PATCH v12 2/9] include: Add a lookup table of sizes, Leonid Bloch, 2018/09/26
- [Qemu-block] [PATCH v12 1/9] qcow2: Options' documentation fixes, Leonid Bloch, 2018/09/26
- [Qemu-block] [PATCH v12 4/9] qcow2: Avoid duplication in setting the refcount cache size, Leonid Bloch, 2018/09/26
- [Qemu-block] [PATCH v12 5/9] qcow2: Assign the L2 cache relatively to the image size, Leonid Bloch, 2018/09/26
- [Qemu-block] [PATCH v12 7/9] qcow2: Resize the cache upon image resizing, Leonid Bloch, 2018/09/26
- [Qemu-block] [PATCH v12 6/9] qcow2: Increase the default upper limit on the L2 cache size, Leonid Bloch, 2018/09/26
- [Qemu-block] [PATCH v12 3/9] qcow2: Make sizes more humanly readable, Leonid Bloch, 2018/09/26
- [Qemu-block] [PATCH v12 8/9] qcow2: Set the default cache-clean-interval to 10 minutes, Leonid Bloch, 2018/09/26
- [Qemu-block] [PATCH v12 9/9] qcow2: Explicit number replaced by a constant, Leonid Bloch, 2018/09/26
- Re: [Qemu-block] [PATCH v12 0/9] Take the image size into account when allocating the L2 cache,
Kevin Wolf <=