<p dir="ltr">hi all.<br>
I have a question about vruntime.<br>
it will not overflow?<br>
i know it's type is u64.<br>
but how about 32bit machine?<br>
i'm wating your help.</p>
<p dir="ltr">Thanks,<br>
Earl</p>
<div class="gmail_quote">2013. 5. 9. 오전 1:01에 <<a href="mailto:kernelnewbies-request@kernelnewbies.org">kernelnewbies-request@kernelnewbies.org</a>>님이 작성:<br type="attribution"><blockquote class="quote" style="margin:0 0 0 .8ex;border-left:1px #ccc solid;padding-left:1ex">
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Today's Topics:<br>
<br>
1. Re: current tty (richard -rw- weinberger)<br>
2. Re: Documentation on device-mapper and friends (Greg Freemyer)<br>
3. Re: Documentation on device-mapper and friends (neha naik)<br>
<br>
<br>
----------------------------------------------------------------------<br>
<br>
Message: 1<br>
Date: Wed, 8 May 2013 14:24:10 +0200<br>
From: richard -rw- weinberger <<a href="mailto:richard.weinberger@gmail.com">richard.weinberger@gmail.com</a>><br>
Subject: Re: current tty<br>
To: Hatte John <<a href="mailto:june.tune.sea@gmail.com">june.tune.sea@gmail.com</a>><br>
Cc: kernelnewbies <<a href="mailto:kernelnewbies@kernelnewbies.org">kernelnewbies@kernelnewbies.org</a>><br>
Message-ID:<br>
<CAFLxGvxeFRS-ojPjXYzMSZ9yRvfpCjLa=+wRo=<a href="mailto:Uu7QiKVdP9bw@mail.gmail.com">Uu7QiKVdP9bw@mail.gmail.com</a>><br>
Content-Type: text/plain; charset=UTF-8<br>
<br>
On Wed, May 8, 2013 at 6:21 AM, Hatte John <<a href="mailto:june.tune.sea@gmail.com">june.tune.sea@gmail.com</a>> wrote:<br>
> Hi?<br>
><br>
> As I know .the /dev/tty is the current task's tty , which is stored to<br>
> current->tty ,<br>
> My question is when does this value is assgined to current->tty ?<br>
<br>
As I told you on IRC, struct task_struct has no ->tty member.<br>
If your custom/old/whatever kernel has, use grep to find out...<br>
<br>
Thanks,<br>
//richard<br>
<br>
<br>
<br>
------------------------------<br>
<br>
Message: 2<br>
Date: Wed, 8 May 2013 10:11:02 -0400<br>
From: Greg Freemyer <<a href="mailto:greg.freemyer@gmail.com">greg.freemyer@gmail.com</a>><br>
Subject: Re: Documentation on device-mapper and friends<br>
To: Gaurav Mahajan <<a href="mailto:gauravmahajan2007@gmail.com">gauravmahajan2007@gmail.com</a>><br>
Cc: amit mehta <<a href="mailto:gmate.amit@gmail.com">gmate.amit@gmail.com</a>>, Linux Kernel List<br>
<<a href="mailto:kernelnewbies@kernelnewbies.org">kernelnewbies@kernelnewbies.org</a>>, Anatol Pomozov<br>
<<a href="mailto:anatol.pomozov@gmail.com">anatol.pomozov@gmail.com</a>>, neha naik <<a href="mailto:nehanaik27@gmail.com">nehanaik27@gmail.com</a>><br>
Message-ID:<br>
<CAGpXXZ+NFme9D=dMMDwZxYmVRxsS29oFqMv=<a href="mailto:VWrAVkvxQUOsig@mail.gmail.com">VWrAVkvxQUOsig@mail.gmail.com</a>><br>
Content-Type: text/plain; charset=ISO-8859-1<br>
<br>
The block layers can be layered both ways. DM is the newer<br>
infrastructure and was created in the early days of 2.6<br>
<br>
If what I was writing could fit into a dm-target, that is what I would do.<br>
<br>
There are significant projects like drbd and mdraid that are not<br>
dm-targets, but I think their is a long term goal to incorporate<br>
mdraid's functionality at a minimum into dm. I doubt drbd is ever<br>
moved to dm. It is just too big of a project and in use in lots of<br>
production server environments.<br>
<br>
Greg<br>
<br>
On Tue, May 7, 2013 at 1:46 AM, Gaurav Mahajan<br>
<<a href="mailto:gauravmahajan2007@gmail.com">gauravmahajan2007@gmail.com</a>> wrote:<br>
> Hi Neha,<br>
><br>
> LVM uses device mapper. Advantages of using device mapper is that you can<br>
> stack different dm-targets on each other.<br>
> I am really not aware of block device drivers.<br>
><br>
> May be Greg can help us understand the actual pros and cons.<br>
><br>
> Thanks,<br>
> Gaurav<br>
><br>
><br>
> On Wed, May 1, 2013 at 9:45 PM, neha naik <<a href="mailto:nehanaik27@gmail.com">nehanaik27@gmail.com</a>> wrote:<br>
>><br>
>> Hi Gaurav,<br>
>> I went through your blog and it is really informative. But after reading<br>
>> that i realized that i have a question:<br>
>> If I want to write a block device driver which is going to sit on lvm<br>
>> (and do some functionality on top of it) then should i go for the block<br>
>> device driver api<br>
>> or write it as a device mapper target. What are the<br>
>> advantages/disadvantages of both the approaches.<br>
>><br>
>> Regards,<br>
>> Neha<br>
>><br>
>><br>
>> On Tue, Apr 30, 2013 at 4:24 AM, Gaurav Mahajan<br>
>> <<a href="mailto:gauravmahajan2007@gmail.com">gauravmahajan2007@gmail.com</a>> wrote:<br>
>>><br>
>>> Hi Amit,<br>
>>><br>
>>> I had compiled some notes on my blog.<br>
>>> Here are some links on writing your own device mapper target.<br>
>>> <a href="http://techgmm.blogspot.in/p/writing-your-own-device-mapper-target.html" target="_blank">http://techgmm.blogspot.in/p/writing-your-own-device-mapper-target.html</a><br>
>>><br>
>>> Concept of device mapper target.<br>
>>> <a href="http://techgmm.blogspot.in/p/device-mapper-layer-explored-every.html" target="_blank">http://techgmm.blogspot.in/p/device-mapper-layer-explored-every.html</a><br>
>>><br>
>>> Thanks,<br>
>>> Gaurav.<br>
>>><br>
>>><br>
>>> On Tue, Apr 30, 2013 at 5:05 AM, Anatol Pomozov<br>
>>> <<a href="mailto:anatol.pomozov@gmail.com">anatol.pomozov@gmail.com</a>> wrote:<br>
>>>><br>
>>>> Hi<br>
>>>><br>
>>>> On Mon, Apr 29, 2013 at 9:51 AM, amit mehta <<a href="mailto:gmate.amit@gmail.com">gmate.amit@gmail.com</a>><br>
>>>> wrote:<br>
>>>> > On Sun, Apr 28, 2013 at 5:24 PM, Greg Freemyer<br>
>>>> > <<a href="mailto:greg.freemyer@gmail.com">greg.freemyer@gmail.com</a>> wrote:<br>
>>>> >> A nice diagram of the overall storage subsystem is at<br>
>>>> >> <a href="http://www.thomas-krenn.com/en/oss/linux-io-stack-diagram.html" target="_blank">http://www.thomas-krenn.com/en/oss/linux-io-stack-diagram.html</a><br>
>>>> >><br>
>>>> >> Dm is just a single block in it, but it can help to see where it fits<br>
>>>> >> in overall.<br>
>>>> >><br>
>>>> >> Btw: that diagram doesn't show the legacy ata driver that creates<br>
>>>> >> /dev/hdx style devices. Has that been dropped while I wasn't paying<br>
>>>> >> attention? I haven't used it in years, but I thought it was still used on<br>
>>>> >> embedded systems.<br>
>>>> >><br>
>>>> ><br>
>>>> > Thank you for sharing the link, but I'm looking for more<br>
>>>> > detailed information on I/O stack in Linux, dm-mapper and<br>
>>>> > multipath in particular.<br>
>>>><br>
>>>> Some docs about multipath can be found here<br>
>>>><br>
>>>> <a href="http://www.sourceware.org/lvm2/wiki/MultipathUsageGuide" target="_blank">http://www.sourceware.org/lvm2/wiki/MultipathUsageGuide</a><br>
>>>> <a href="http://christophe.varoqui.free.fr/refbook.html" target="_blank">http://christophe.varoqui.free.fr/refbook.html</a><br>
>>>><br>
>>>> The userspace part for tools is here<br>
>>>> <a href="http://sourceware.org/lvm2/" target="_blank">http://sourceware.org/lvm2/</a><br>
>>>><br>
>>>> _______________________________________________<br>
>>>> Kernelnewbies mailing list<br>
>>>> <a href="mailto:Kernelnewbies@kernelnewbies.org">Kernelnewbies@kernelnewbies.org</a><br>
>>>> <a href="http://lists.kernelnewbies.org/mailman/listinfo/kernelnewbies" target="_blank">http://lists.kernelnewbies.org/mailman/listinfo/kernelnewbies</a><br>
>>><br>
>>><br>
>>><br>
>>> _______________________________________________<br>
>>> Kernelnewbies mailing list<br>
>>> <a href="mailto:Kernelnewbies@kernelnewbies.org">Kernelnewbies@kernelnewbies.org</a><br>
>>> <a href="http://lists.kernelnewbies.org/mailman/listinfo/kernelnewbies" target="_blank">http://lists.kernelnewbies.org/mailman/listinfo/kernelnewbies</a><br>
>>><br>
>><br>
><br>
<br>
<br>
<br>
------------------------------<br>
<br>
Message: 3<br>
Date: Wed, 8 May 2013 09:15:26 -0600<br>
From: neha naik <<a href="mailto:nehanaik27@gmail.com">nehanaik27@gmail.com</a>><br>
Subject: Re: Documentation on device-mapper and friends<br>
To: Greg Freemyer <<a href="mailto:greg.freemyer@gmail.com">greg.freemyer@gmail.com</a>><br>
Cc: amit mehta <<a href="mailto:gmate.amit@gmail.com">gmate.amit@gmail.com</a>>, Linux Kernel List<br>
<<a href="mailto:kernelnewbies@kernelnewbies.org">kernelnewbies@kernelnewbies.org</a>>, Anatol Pomozov<br>
<<a href="mailto:anatol.pomozov@gmail.com">anatol.pomozov@gmail.com</a>>, Gaurav Mahajan<br>
<<a href="mailto:gauravmahajan2007@gmail.com">gauravmahajan2007@gmail.com</a>><br>
Message-ID:<br>
<CAOb=_xKRuH4jzD=aue-HJP+=DxguPYwuaqie=<a href="mailto:sMvvYytvoXCcA@mail.gmail.com">sMvvYytvoXCcA@mail.gmail.com</a>><br>
Content-Type: text/plain; charset="iso-8859-1"<br>
<br>
Hi Greg,<br>
Thanks for the information. I have another question :).<br>
Is there some less flexibility if we use device mapper target?<br>
For example in block device driver you can use the api such that it won't<br>
use the OS io scheduler, so the io comes directly to the block device<br>
driver through the 'make_request' call. With the device mapper i don't<br>
think that happens(looking at the api calls). Does this mean that stuff<br>
like io scheduling. barrier control etc is done<br>
by the device mapper itself and we can focus only on 'mapping' the io.<br>
<br>
Regards,<br>
Neha<br>
<br>
On Wed, May 8, 2013 at 8:11 AM, Greg Freemyer <<a href="mailto:greg.freemyer@gmail.com">greg.freemyer@gmail.com</a>>wrote:<br>
<br>
> The block layers can be layered both ways. DM is the newer<br>
> infrastructure and was created in the early days of 2.6<br>
><br>
> If what I was writing could fit into a dm-target, that is what I would do.<br>
><br>
> There are significant projects like drbd and mdraid that are not<br>
> dm-targets, but I think their is a long term goal to incorporate<br>
> mdraid's functionality at a minimum into dm. I doubt drbd is ever<br>
> moved to dm. It is just too big of a project and in use in lots of<br>
> production server environments.<br>
><br>
> Greg<br>
><br>
> On Tue, May 7, 2013 at 1:46 AM, Gaurav Mahajan<br>
> <<a href="mailto:gauravmahajan2007@gmail.com">gauravmahajan2007@gmail.com</a>> wrote:<br>
> > Hi Neha,<br>
> ><br>
> > LVM uses device mapper. Advantages of using device mapper is that you can<br>
> > stack different dm-targets on each other.<br>
> > I am really not aware of block device drivers.<br>
> ><br>
> > May be Greg can help us understand the actual pros and cons.<br>
> ><br>
> > Thanks,<br>
> > Gaurav<br>
> ><br>
> ><br>
> > On Wed, May 1, 2013 at 9:45 PM, neha naik <<a href="mailto:nehanaik27@gmail.com">nehanaik27@gmail.com</a>> wrote:<br>
> >><br>
> >> Hi Gaurav,<br>
> >> I went through your blog and it is really informative. But after<br>
> reading<br>
> >> that i realized that i have a question:<br>
> >> If I want to write a block device driver which is going to sit on lvm<br>
> >> (and do some functionality on top of it) then should i go for the block<br>
> >> device driver api<br>
> >> or write it as a device mapper target. What are the<br>
> >> advantages/disadvantages of both the approaches.<br>
> >><br>
> >> Regards,<br>
> >> Neha<br>
> >><br>
> >><br>
> >> On Tue, Apr 30, 2013 at 4:24 AM, Gaurav Mahajan<br>
> >> <<a href="mailto:gauravmahajan2007@gmail.com">gauravmahajan2007@gmail.com</a>> wrote:<br>
> >>><br>
> >>> Hi Amit,<br>
> >>><br>
> >>> I had compiled some notes on my blog.<br>
> >>> Here are some links on writing your own device mapper target.<br>
> >>><br>
> <a href="http://techgmm.blogspot.in/p/writing-your-own-device-mapper-target.html" target="_blank">http://techgmm.blogspot.in/p/writing-your-own-device-mapper-target.html</a><br>
> >>><br>
> >>> Concept of device mapper target.<br>
> >>> <a href="http://techgmm.blogspot.in/p/device-mapper-layer-explored-every.html" target="_blank">http://techgmm.blogspot.in/p/device-mapper-layer-explored-every.html</a><br>
> >>><br>
> >>> Thanks,<br>
> >>> Gaurav.<br>
> >>><br>
> >>><br>
> >>> On Tue, Apr 30, 2013 at 5:05 AM, Anatol Pomozov<br>
> >>> <<a href="mailto:anatol.pomozov@gmail.com">anatol.pomozov@gmail.com</a>> wrote:<br>
> >>>><br>
> >>>> Hi<br>
> >>>><br>
> >>>> On Mon, Apr 29, 2013 at 9:51 AM, amit mehta <<a href="mailto:gmate.amit@gmail.com">gmate.amit@gmail.com</a>><br>
> >>>> wrote:<br>
> >>>> > On Sun, Apr 28, 2013 at 5:24 PM, Greg Freemyer<br>
> >>>> > <<a href="mailto:greg.freemyer@gmail.com">greg.freemyer@gmail.com</a>> wrote:<br>
> >>>> >> A nice diagram of the overall storage subsystem is at<br>
> >>>> >> <a href="http://www.thomas-krenn.com/en/oss/linux-io-stack-diagram.html" target="_blank">http://www.thomas-krenn.com/en/oss/linux-io-stack-diagram.html</a><br>
> >>>> >><br>
> >>>> >> Dm is just a single block in it, but it can help to see where it<br>
> fits<br>
> >>>> >> in overall.<br>
> >>>> >><br>
> >>>> >> Btw: that diagram doesn't show the legacy ata driver that creates<br>
> >>>> >> /dev/hdx style devices. Has that been dropped while I wasn't<br>
> paying<br>
> >>>> >> attention? I haven't used it in years, but I thought it was still<br>
> used on<br>
> >>>> >> embedded systems.<br>
> >>>> >><br>
> >>>> ><br>
> >>>> > Thank you for sharing the link, but I'm looking for more<br>
> >>>> > detailed information on I/O stack in Linux, dm-mapper and<br>
> >>>> > multipath in particular.<br>
> >>>><br>
> >>>> Some docs about multipath can be found here<br>
> >>>><br>
> >>>> <a href="http://www.sourceware.org/lvm2/wiki/MultipathUsageGuide" target="_blank">http://www.sourceware.org/lvm2/wiki/MultipathUsageGuide</a><br>
> >>>> <a href="http://christophe.varoqui.free.fr/refbook.html" target="_blank">http://christophe.varoqui.free.fr/refbook.html</a><br>
> >>>><br>
> >>>> The userspace part for tools is here<br>
> >>>> <a href="http://sourceware.org/lvm2/" target="_blank">http://sourceware.org/lvm2/</a><br>
> >>>><br>
> >>>> _______________________________________________<br>
> >>>> Kernelnewbies mailing list<br>
> >>>> <a href="mailto:Kernelnewbies@kernelnewbies.org">Kernelnewbies@kernelnewbies.org</a><br>
> >>>> <a href="http://lists.kernelnewbies.org/mailman/listinfo/kernelnewbies" target="_blank">http://lists.kernelnewbies.org/mailman/listinfo/kernelnewbies</a><br>
> >>><br>
> >>><br>
> >>><br>
> >>> _______________________________________________<br>
> >>> Kernelnewbies mailing list<br>
> >>> <a href="mailto:Kernelnewbies@kernelnewbies.org">Kernelnewbies@kernelnewbies.org</a><br>
> >>> <a href="http://lists.kernelnewbies.org/mailman/listinfo/kernelnewbies" target="_blank">http://lists.kernelnewbies.org/mailman/listinfo/kernelnewbies</a><br>
> >>><br>
> >><br>
> ><br>
><br>
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</blockquote></div>