> On 14 Mar 2019, at 07.22, Javier González <[email protected]> wrote: > >> On 14 Mar 2019, at 07.17, Marcin Dziegielewski >> <[email protected]> wrote: >> >> In some cases write thread migration between cpus can cause >> sending writes in improper order and in consequence a lot of >> errors from device. >> >> Write thread affinity to particular cpu prevent before it. >> >> Signed-off-by: Marcin Dziegielewski <[email protected]> >> --- >> drivers/lightnvm/pblk-init.c | 30 +++++++++++++++++++++++++++++- >> drivers/lightnvm/pblk.h | 1 + >> drivers/nvme/host/lightnvm.c | 1 + >> include/linux/lightnvm.h | 2 ++ >> 4 files changed, 33 insertions(+), 1 deletion(-) >> >> diff --git a/drivers/lightnvm/pblk-init.c b/drivers/lightnvm/pblk-init.c >> index 81e8ed4..bd25004 100644 >> --- a/drivers/lightnvm/pblk-init.c >> +++ b/drivers/lightnvm/pblk-init.c >> @@ -21,6 +21,8 @@ >> >> #include "pblk.h" >> #include "pblk-trace.h" >> +#include <linux/cpumask.h> >> +#include <linux/numa.h> >> >> static unsigned int write_buffer_size; >> >> @@ -47,6 +49,8 @@ struct pblk_global_caches { >> >> struct bio_set pblk_bio_set; >> >> +cpumask_t free_cpumask; >> + >> static int pblk_rw_io(struct request_queue *q, struct pblk *pblk, >> struct bio *bio) >> { >> @@ -1098,6 +1102,9 @@ static int pblk_lines_init(struct pblk *pblk) >> >> static int pblk_writer_init(struct pblk *pblk) >> { >> + cpumask_t tmp_cpumask, cpumask; >> + int cpu; >> + >> pblk->writer_ts = kthread_create(pblk_write_ts, pblk, "pblk-writer-t"); >> if (IS_ERR(pblk->writer_ts)) { >> int err = PTR_ERR(pblk->writer_ts); >> @@ -1108,6 +1115,22 @@ static int pblk_writer_init(struct pblk *pblk) >> return err; >> } >> >> + cpumask_and(&tmp_cpumask, cpumask_of_node(pblk->dev->parent->node), >> + cpu_online_mask); >> + cpumask_and(&cpumask, &tmp_cpumask, &free_cpumask); >> + >> + if (!cpumask_weight(&free_cpumask)) { >> + free_cpumask = CPU_MASK_ALL; >> + cpumask_and(&cpumask, &tmp_cpumask, &free_cpumask); >> + } >> + >> + cpu = cpumask_last(&cpumask); >> + >> + kthread_bind(pblk->writer_ts, cpu); >> + >> + cpumask_clear_cpu(cpu, &free_cpumask); >> + pblk->writer_cpu = cpu; >> + >> timer_setup(&pblk->wtimer, pblk_write_timer_fn, 0); >> mod_timer(&pblk->wtimer, jiffies + msecs_to_jiffies(100)); >> >> @@ -1126,8 +1149,11 @@ static void pblk_writer_stop(struct pblk *pblk) >> "Stopping not fully synced write buffer\n"); >> >> del_timer_sync(&pblk->wtimer); >> - if (pblk->writer_ts) >> + if (pblk->writer_ts) { >> + set_cpus_allowed_ptr(pblk->writer_ts, cpu_online_mask); >> kthread_stop(pblk->writer_ts); >> + cpumask_set_cpu(pblk->writer_cpu, &free_cpumask); >> + } >> } >> >> static void pblk_free(struct pblk *pblk) >> @@ -1328,6 +1354,8 @@ static int __init pblk_module_init(void) >> { >> int ret; >> >> + free_cpumask = CPU_MASK_ALL; >> + >> ret = bioset_init(&pblk_bio_set, BIO_POOL_SIZE, 0, 0); >> if (ret) >> return ret; >> diff --git a/drivers/lightnvm/pblk.h b/drivers/lightnvm/pblk.h >> index 381f074..650f983 100644 >> --- a/drivers/lightnvm/pblk.h >> +++ b/drivers/lightnvm/pblk.h >> @@ -690,6 +690,7 @@ struct pblk { >> atomic_t inflight_io; /* General inflight I/O counter */ >> >> struct task_struct *writer_ts; >> + int writer_cpu; >> >> /* Simple translation map of logical addresses to physical addresses. >> * The logical addresses is known by the host system, while the physical >> diff --git a/drivers/nvme/host/lightnvm.c b/drivers/nvme/host/lightnvm.c >> index 949e29e..971a19f 100644 >> --- a/drivers/nvme/host/lightnvm.c >> +++ b/drivers/nvme/host/lightnvm.c >> @@ -982,6 +982,7 @@ int nvme_nvm_register(struct nvme_ns *ns, char >> *disk_name, int node) >> memcpy(dev->name, disk_name, DISK_NAME_LEN); >> dev->ops = &nvme_nvm_dev_ops; >> dev->private_data = ns; >> + dev->node = node; >> ns->ndev = dev; >> >> return nvm_register(dev); >> diff --git a/include/linux/lightnvm.h b/include/linux/lightnvm.h >> index 5d865a5..312029e 100644 >> --- a/include/linux/lightnvm.h >> +++ b/include/linux/lightnvm.h >> @@ -427,6 +427,8 @@ struct nvm_dev { >> char name[DISK_NAME_LEN]; >> void *private_data; >> >> + int node; >> + >> void *rmap; >> >> struct mutex mlock; >> -- >> 1.8.3.1 > > We have a per-CPU semaphore that only allows to send a single I/O in > order to prevent write pointer violations. Are you seeing this error, or > is it theoretical? > > Javier
I meant per PU (parallel unit)…
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