Re: [PATCH v2 6/9] n_tty: Process echoes in blocks

[Date Prev][Date Next][Thread Prev][Thread Next][Date Index][Thread Index]

 



On 07/23/2013 07:53 PM, Greg Kroah-Hartman wrote:
On Sat, Jun 15, 2013 at 10:04:26AM -0400, Peter Hurley wrote:
Byte-by-byte echo output is painfully slow, requiring a lock/unlock
cycle for every input byte.

Instead, perform the echo output in blocks of 256 characters, and
at least once per flip buffer receive. Enough space is reserved in
the echo buffer to guarantee a full block can be saved without
overrunning the echo output. Overrun is prevented by discarding
the oldest echoes until enough space exists in the echo buffer
to receive at least a full block of new echoes.

I'm a bit worried about this, I wonder if anything is expecting the
echos to not come in "bursts" like this, but I really can't think of why
they would want that.

The block size for echoes is trivially settable so if you'd prefer a
smaller value than every 256 chars, I could send a patch for a value
you are more comfortable with - 64 chars, 32 chars, whatever.

I picked that value from casual performance testing and that it
coincides with the smallest possible flip buffer; ie., echo blocks are
retired at the same rate as flip buffers when receiving is not
saturated.

So let's apply it and see what breaks!  :)

I'm ready :)

Regards,
Peter Hurley

--
To unsubscribe from this list: send the line "unsubscribe linux-serial" in
the body of a message to majordomo@xxxxxxxxxxxxxxx
More majordomo info at  http://vger.kernel.org/majordomo-info.html




[Index of Archives]     [Kernel Newbies]     [Security]     [Netfilter]     [Bugtraq]     [Linux PPP]     [Linux FS]     [Yosemite News]     [MIPS Linux]     [ARM Linux]     [Linux Security]     [Linux RAID]     [Samba]     [Video 4 Linux]     [Linmodem]     [Device Mapper]     [Linux Kernel for ARM]

  Powered by Linux