Using a slow serial console with sync_console on SMP leaves an
authorkaf24@firebug.cl.cam.ac.uk <kaf24@firebug.cl.cam.ac.uk>
Sat, 3 Dec 2005 09:44:01 +0000 (10:44 +0100)
committerkaf24@firebug.cl.cam.ac.uk <kaf24@firebug.cl.cam.ac.uk>
Sat, 3 Dec 2005 09:44:01 +0000 (10:44 +0100)
commit25df6829ebc3eeeb56c6cea8a3376d510581d7b3
treec32028d84bbe2a0f61c55d8ef49be3e3c4e2ea32
parentffa06621c6b2b9a1c186a919154eb8d3ec3d453d
Using a slow serial console with sync_console on SMP leaves an
unusable system: it gets into a flood of

Timer ISR/0: Time went backwards: delta=-3566279 cpu_delta=16433721
shadow=2019998373 off=420435384 processed=2444000000
cpu_processed=2424000000
 0: 2424000000
 1: 2444000000

messages which swamps the console and leaves things almost, but not
quite, completely hung.  It is a simple matter to ratelimit these
printks, which completely eliminates the problem.
linux-2.6-xen-sparse/arch/xen/i386/kernel/time.c