On 2011-10-03 13:23, Harsh Prateek Bora wrote: > SynthFS uses rwlocks, which raise the need of a generic QemuRWLock APIs. > This patchset introduces the same making necessary changes to relevant code. Is the impact of using a plain mutex measurable with 9pfs? Usually it takes very heavy write sections or highly concurrent read sections to actually make a difference. Looking at the cited code, I would dare to rule out the former (even more if the malloc was moved out of the critical section). But I cannot assess the latter. If it does matter, I would vote for introducing RCU directly. Jan