Messages in this thread | | | Date | Tue, 02 Apr 2013 16:36:30 +0300 | From | Adrian Hunter <> | Subject | Re: [PATCH v2] wait while adding MMC host to ensure root mounts |
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On 27/03/13 13:57, Chris Ball wrote: > Hi, > > On Wed, Mar 27 2013, Ulf Hansson wrote: >> I noticed you merged this. I thought the idea was to use the rootwait >> or rootdelay? > > That's necessary before the patch, but it would be better if we didn't > have to pass rootwait, all else being equal. > >> Moreover, this patch will have bad impact on booting the kernel, since >> every host device that has scheduled a detect work from it's probe >> function will also wait for it to finish. Even if it is the boot >> device of not. If this is needed, I would prefer that a host cap is >> used. > > I see, you're worried about a performance regression where every boot > takes longer than it used to while MMC quiesces. That's fair. Do you > think you could tell me how much delay this adds to a boot for you, so > that we can consider whether the usability improvement is worth it? > > If the delay's significant, I agree with you and will revert this patch.
On my system it is significant:
Before the patch:
[ 1.625623] VFS: Mounted root (ext4 filesystem) readonly on device 179:2.
After the patch:
[ 1.935851] VFS: Mounted root (ext4 filesystem) readonly on device 179:2.
That is an addition of 310 ms which is 19% performance degradation.
Please revert the patch.
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