On Mon, Jan 16, 2023 at 04:38:01AM +0000, Matthew Wilcox wrote:
> On Mon, Jan 16, 2023 at 11:16:13AM +0800, maobibo wrote:
> > Hongchen,
> >
> > I have a glance with this patch, it simply replaces with
> > spinlock_irqsave with mutex lock. There may be performance
> > improvement with two processes competing with pipe, however
> > for N processes, there will be complex context switches
> > and ipi interruptts.
> >
> > Can you find some cases with more than 2 processes competing
> > pipe, rather than only unixbench?
>
> What real applications have pipes with more than 1 writer & 1 reader?
> I'm OK with slowing down the weird cases if the common cases go faster.
>From commit 0ddad21d3e99c743a3aa473121dc5561679e26bb:
While this isn't a common occurrence in the traditional "use a pipe as a
data transport" case, where you typically only have a single reader and
a single writer process, there is one common special case: using a pipe
as a source of "locking tokens" rather than for data communication.
In particular, the GNU make jobserver code ends up using a pipe as a way
to limit parallelism, where each job consumes a token by reading a byte
from the jobserver pipe, and releases the token by writing a byte back
to the pipe.
