Re: [PATCH] v5 RCU: the bloatwatch edition

[David Howells <dhowells@redhat.com>]

Paul E. McKenney <paulmck@linux.vnet.ibm.com> wrote:

> This patch is a version of RCU designed for (!SMP && EMBEDDED)
> provided as a proof of concept of a small-footprint RCU implementation.
> In particular, the implementation of synchronize_rcu() is extremely
> lightweight and high performance.  It passes rcutorture testing in each
> of the four relevant configurations (combinations of NO_HZ and PREEMPT)
> on x86.  This saves 1263 bytes compared to Classic RCU, and more than
> three kilobytes compared to Hierarchical RCU (updated to 2.6.30):

On FRV:

	CONFIG_CLASSIC_RCU=y

	   text    data     bss     dec     hex filename
	    884      32      20     936     3a8 kernel/rcupdate.o
	   2616     184       0    2800     af0 kernel/rcuclassic.o

	CONFIG_TREE_RCU=y

	   text    data     bss     dec     hex filename
	    884      32      20     936     3a8 kernel/rcupdate.o
	   4068     384       0    4452    1164 kernel/rcutree.o

	CONFIG_TINY_RCU=y

	   text    data     bss     dec     hex filename
	    836      32      20     888     378 kernel/rcupdate.o
	    816      24       0     840     348 kernel/rcutiny.o

On MN10300:

	CONFIG_CLASSIC_RCU=y

	   text    data     bss     dec     hex filename
	    900      28      48     976     3d0 kernel/rcupdate.o
	   1777     184       0    1961     7a9 kernel/rcuclassic.o

	CONFIG_TREE_RCU=y

	   text    data     bss     dec     hex filename
	    900      28      48     976     3d0 kernel/rcupdate.o
	   2733     384       0    3117     c2d kernel/rcutree.o

	CONFIG_PREEMPT_RCU=y

	   text    data     bss     dec     hex filename
	    961      28      48    1037     40d kernel/rcupdate.o
	   3314     128       8    3450     d7a kernel/rcupreempt.o

	CONFIG_TINY_RCU=y

	   text    data     bss     dec     hex filename
	    865      28      48     941     3ad kernel/rcupdate.o
	    500      24       0     524     20c kernel/rcutiny.o

> Signed-off-by: Paul E. McKenney <paulmck@linux.vnet.ibm.com>

Acked-by: David Howells <dhowells@redhat.com