基于ZNS SSD模拟器的LSM Tree适配设计

# FEMU-Sim An SSD simulator derived from FEMU, so that we don't need to mess with VMs. ## Building ``` mkdir build cd build cmake .. make ``` A simple test program can be found under `build/bin`. ## Porting an FTL from FEMU Make sure to check over-provision rate: ```C static void check_params(struct ssdparams *spp) { ftl_assert(spp->device_size <= spp->flash_size); } ``` Replace all `qemu_thread_create` with `pthread_create` and all `QemuThread` with `pthread_t`: ```C void ssd_init(FemuCtrl *n) { /* ...... */ assert(pthread_create(&ssd->ftl_thread, NULL, ftl_thread, n) == 0); /* ...... */ } ``` Iteration boundary in `ftl_thread`: ```C static void *ftl_thread(void *arg) { /* ...... */ while (1) { for (int i = 0; i < n->num_poller; i++) { /* ...... */ } } /* ...... */ } ``` Disable latency emulation when needed: ```C static void *ftl_thread(void *arg) { /* ...... */ if (n->enable_latency) { req->reqlat = lat; req->expire_time += lat; } /* ...... */ } ```