On Fri, Feb 26, 2016 at 11:38 AM, Andy Grover <agrover@xxxxxxxxxx> wrote: > On 02/25/2016 06:03 PM, Sheng Yang wrote: >>>>> >>>>> -#define DATA_SIZE (257 * 4096) >>>>> +#define DATA_SIZE (DATA_BLOCK_BITS * DATA_BLOCK_SIZE) >>>> >>>> >>>> >>>> So the reason this was 25*7* was because in testing I saw repeated >>>> lengths >>>> of size 512KiB, and due to the ring not being able to be completely used >>>> (a >>>> limitation of the circular buffer logic) this would result in only one >>>> request and the second having to wait. Another page allowed 2 to fit at >>>> once >>>> :) so now that we're not using a ring any more this can probably just be >>>> 256 >>>> and still fit 2 512KiB allocations. >>>> >>> >>> Sure. Would update. >> >> >> In fact I just run another test again 256 * 4096, and found there are >> many requests just 1MB long. So the following warning is triggered: >> >> "TCMU: Request of size 4160/1048576 may be too big for 65408/1048576 >> cmd/data ring buffers." >> >> Probably we want to increase the buffer size a bit? >> >> But also it shows that we cannot accommodate all the upper layer >> request in the buffer... There is no way we can allocate 1MB buffer >> for each request. > > > I thought we could allocate an exactly 1MB buffer, with your changes, no? > That warning message may need to be changed. Yes we can, it make sense to remove the warning message. Though I am not quite comfortable with one request fill the whole buffer, because we would only able to handle one request with the whole ring. Like we discussed in http://comments.gmane.org/gmane.linux.scsi.target.devel/11107 , we should have a ring buffer fits all requests from upper layer. --Sheng > > -- Andy > -- To unsubscribe from this list: send the line "unsubscribe target-devel" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
