We have a fairly high end box running mysqld 5.5.20.
The cpu configuration is dual quad core xeons.
It has 32 gb ram.
It has a quad intel ssd configuration running raid 0+1.
On a fairly busy service what starts to happen is that after about 18 to 24 hours of being up, once in a while, every few hours, there will be a 1min period where ALL inserts will start stacking. The strange thing is that using mytop even memory table inserts / updates are shown as executing for 'many' seconds.
More ofen then not even without a restart it will return to normal.... only to do it again.
A restart always fixed the issue, for another 18 to 24 hours.
All munins look ok.