bhyve: TRIM support in AHCI controller

[Allan Jude]

On 2020-03-19 08:54, Wanpeng Qian wrote:
> Hi all
> 
> I found the output of diskinfo inside VM of AHCI disk as follow, no
> TRIM support.
> root at smart:~ #  diskinfo -v ada0
> ada0
> 512          # sectorsize
> 21474836480 # mediasize in bytes (20G)
> 41943040    # mediasize in sectors
> 131072      # stripesize
> 0            # stripeoffset
> 41610        # Cylinders according to firmware.
> 16          # Heads according to firmware.
> 63          # Sectors according to firmware.
> BHYVE SATA DISK # Disk descr.
> BHYVE-0B98-104F-E9A7 # Disk ident.
> No          # TRIM/UNMAP support
> 0            # Rotation rate in RPM
> Not_Zoned    # Zone Mode
> 
> Also camcontrol identify ada0 -v show not support of TRIM
> 
> Data Set Management (DSM/TRIM) no
> 
> I check to pci_ahci.c, TRIM support is decided by block_if.c's candelete flag.
> while candelete is decided here
> 
>                 strlcpy(arg.name, "GEOM::candelete", sizeof(arg.name));
>                 arg.len = sizeof(arg.value.i);
>                 if (ioctl(fd, DIOCGATTR, &arg) == 0)
>                         candelete = arg.value.i;
> 
> Obvious file backend will not have the candelete flag.
> 
> If the backend storage support TRIM, I think we should present TRIM
> ability to VM.
> Any better idea to check whether backend storage support TRIM or not,
> so we can enable it.
> 
> Thanks.
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> 

I have updated my patch to add TRIM support to the bhyve block interface
here:

https://reviews.freebsd.org/D21707

I am working on an update to the virtio driver, to make FreeBSD guests
able to TRIM if the hypervisor supports it as well:

https://reviews.freebsd.org/D21708


-- 
Allan Jude

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