[PATCH 2/2] mtip32xx: mtip32xx: Disable TRIM support

[PATCH 2/2] mtip32xx: mtip32xx: Disable TRIM support

[Asai Thambi S P]

Temporarily disabling TRIM support until TRIM related issues
are addressed in the firmware.

Signed-off-by: Asai Thambi S P <asamymuthupa@micron.com>
---
 drivers/block/mtip32xx/mtip32xx.c |    2 ++
 1 files changed, 2 insertions(+), 0 deletions(-)

diff --git a/drivers/block/mtip32xx/mtip32xx.c b/drivers/block/mtip32xx/mtip32xx.c
index d11ea92..53bad62 100644
--- a/drivers/block/mtip32xx/mtip32xx.c
+++ b/drivers/block/mtip32xx/mtip32xx.c
@@ -1560,10 +1560,12 @@ static int mtip_get_identify(struct mtip_port *port, void __user *user_buffer)
 	}
 #endif
 
+#ifdef MTIP_TRIM /* Disabling TRIM support temporarily */
 	/* Demux ID.DRAT & ID.RZAT to determine trim support */
 	if (port->identify[69] & (1 << 14) && port->identify[69] & (1 << 5))
 		port->dd->trim_supp = true;
 	else
+#endif
 		port->dd->trim_supp = false;
 
 	/* Set the identify buffer as valid. */
-- 
1.7.1

Re: [PATCH 2/2] mtip32xx: mtip32xx: Disable TRIM support

[Jens Axboe]

On Fri, Apr 12 2013, Asai Thambi S P wrote:
> 
> Temporarily disabling TRIM support until TRIM related issues
> are addressed in the firmware.

How serious is this? We do have released kernels out there with the
driver, you might want to consider a stable backport too.

Anyway, applied for 3.10.

-- 
Jens Axboe

RE: [PATCH 2/2] mtip32xx: mtip32xx: Disable TRIM support

[Sam Bradshaw (sbradshaw)]

> On Fri, Apr 12 2013, Asai Thambi S P wrote:
> >
> > Temporarily disabling TRIM support until TRIM related issues
> > are addressed in the firmware.
> 
> How serious is this? We do have released kernels out there with the
> driver, you might want to consider a stable backport too.

It's a performance issue, not data integrity.  Since the ATA trim command
is non-queueable, IO traffic must halt while the trim is outstanding.  A 
filesystem that is actively trimming sectors is effectively duty cycling 
the IO path on this part.  We are working to shrink the trim command 
latency while also investigating whether some sort of offline trim is more
appropriate.

Given the incremental endurance gain for trim on 34nm SLC vs the severe 
throughput degradation under some workloads, it seemed prudent to disable
the feature.

If you think that warrants a stable backport, just let me or Asai know.

-Sam

Re: [PATCH 2/2] mtip32xx: mtip32xx: Disable TRIM support

[Asai Thambi S P]

On 4/14/2013 1:55 PM, Jens Axboe wrote:

> On Fri, Apr 12 2013, Asai Thambi S P wrote:
>>
>> Temporarily disabling TRIM support until TRIM related issues
>> are addressed in the firmware.
> 
> How serious is this? We do have released kernels out there with the
> driver, you might want to consider a stable backport too.
> 
> Anyway, applied for 3.10.
> 

Added TRIM support in 3.9 merge window. If this trivial change could be
pushed, it would be good. Otherwise, I can backport to stable 3.9 when released.

--
regards,
asai