L4Re IPC share memory that share file in one Linux filesystem and be visible to other Linuxes

[Matthias Lange]

Hi,

On 07/06/2017 02:14 PM, Joyce Peng(彭美僑) wrote:
> Yes, I know this easiest way that mount filesystem via NFS, NBD or
> SMB. But I have a mission to evaluate the IPC performance between two
> Linuxes that run on top of Fiasco.OC. So our evaluated environment is
> run a media player in one Linux and this player will access media
> data in other Linux. And we use uvmm to run two vms that run Linux
> respectively.

Sorry, I'am a bit confused here. What do you mean if you say you want to
measure IPC performance between two Linuxes? What does IPC in this
context mean?

If you measure the communication performance between two Linux VMs
running with uvmm you have no direct (L4) IPC between Linux processes in
both VMs. You will (not only) add a lot of overhead because of VM exits
and resumes.

If you are interested in raw IPC performance, why don't you just use
pingpong?

Best,
Matthias.


> 
> Regards, Joyce.Peng(彭美僑)
> 
> -----Original Message----- From: Matthias Lange
> [mailto:matthias.lange at kernkonzept.com] Sent: Thursday, July 06, 2017
> 4:58 AM To: l4-hackers at os.inf.tu-dresden.de Cc: Joyce Peng(彭美僑) 
> Subject: Re: L4Re IPC share memory that share file in one Linux
> filesystem and be visible to other Linuxes
> 
> Hi,
> 
> On 07/05/2017 05:47 AM, Joyce Peng(彭美僑) wrote:
>> Hi L4,
>> 
>> I want to share a file in one Linux filesystem and be visible to 
>> other Linuxes that all run on top Fiasco.OC. It seems an IPC 
>> communication between L4re vm tasks. And access a file in Linux 
>> filesystem is a mechanism of kernel block device driver. But I only
>>  notice two char device drivers that use L4re library l4shmc in 
>> L4linux. It is l4ser_shm and l4shmnet. May you give some
>> information about this work how to work. Thanks.
> 
> Have you thought about how to syncronize access to the filesystem
> between the two VMs?
> 
> The easiest approach would be to setup a (virtual) network connection
> between the two VMs and let one VM provide the filesystem via NFS,
> NBD or SMB.
> 
> Regards, Matthias.
> 
>> 
>> Joyce.peng(彭美僑