On Thu, Dec 10, 2020 at 12:26:01PM +0100, Daniel Vetter wrote:
On Thu, Dec 10, 2020 at 11:55 AM Greg KH gregkh@linuxfoundation.org wrote:
On Thu, Dec 10, 2020 at 11:27:27AM +0100, Daniel Vetter wrote:
On Thu, Dec 10, 2020 at 11:10:45AM +0100, Greg KH wrote:
On Thu, Dec 10, 2020 at 10:58:50AM +0100, Christian König wrote:
In general a good idea, but I have a few concern/comments here.
Am 10.12.20 um 05:43 schrieb Hridya Valsaraju:
This patch allows statistics to be enabled for each DMA-BUF in sysfs by enabling the config CONFIG_DMABUF_SYSFS_STATS.
The following stats will be exposed by the interface:
/sys/kernel/dmabuf/<inode_number>/exporter_name /sys/kernel/dmabuf/<inode_number>/size /sys/kernel/dmabuf/<inode_number>/dev_map_info
The inode_number is unique for each DMA-BUF and was added earlier [1] in order to allow userspace to track DMA-BUF usage across different processes.
Currently, this information is exposed in /sys/kernel/debug/dma_buf/bufinfo. However, since debugfs is considered unsafe to be mounted in production, it is being duplicated in sysfs.
Mhm, this makes it part of the UAPI. What is the justification for this?
In other words do we really need those debug information in a production environment?
Production environments seem to want to know who is using up memory :)
This only shows shared memory, so it does smell a lot like $specific_issue and we're designing a narrow solution for that and then have to carry it forever.
I think the "issue" is that this was a feature from ion that people "missed" in the dmabuf move. Taking away the ability to see what kind of allocations were being made didn't make a lot of debugging tools happy :(
If this is just for dma-heaps then why don't we add the stuff back over there? It reinforces more that the android gpu stack and the non-android gpu stack on linux are fairly different in fundamental ways, but that's not really new.
Back "over where"?
dma-bufs are not only used for the graphics stack on android from what I can tell, so this shouldn't be a gpu-specific issue.
confused,
greg k-h