Messages in this thread | | | Date | Wed, 14 Jul 2021 11:16:04 -0300 | From | Arnaldo Carvalho de Melo <> | Subject | Re: [RFC PATCH 01/10] perf workqueue: threadpool creation and destruction |
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Em Tue, Jul 13, 2021 at 02:11:12PM +0200, Riccardo Mancini escreveu: > The workqueue library is made up by two components: > - threadpool: handles the lifetime of the threads > - workqueue: handles work distribution among the threads > > This first patch introduces the threadpool, starting from its creation > and destruction functions. > Thread management is based on the prototype from Alexey: > https://lore.kernel.org/lkml/cover.1625227739.git.alexey.v.bayduraev@linux.intel.com/ > > Each thread in the threadpool executes the same function (aka task) > with a different argument tidx. > Threads use a pair of pipes to communicate with the main process. > The threadpool is static (all threads will be spawned at the same time). > Future work could include making it resizable and adding affinity support > (as in Alexey prototype). > > Suggested-by: Alexey Bayduraev <alexey.v.bayduraev@linux.intel.com> > Signed-off-by: Riccardo Mancini <rickyman7@gmail.com> > --- > tools/perf/util/Build | 1 + > tools/perf/util/workqueue/Build | 1 + > tools/perf/util/workqueue/threadpool.c | 175 +++++++++++++++++++++++++ > tools/perf/util/workqueue/threadpool.h | 19 +++ > 4 files changed, 196 insertions(+) > create mode 100644 tools/perf/util/workqueue/Build > create mode 100644 tools/perf/util/workqueue/threadpool.c > create mode 100644 tools/perf/util/workqueue/threadpool.h > > diff --git a/tools/perf/util/Build b/tools/perf/util/Build > index 2d4fa13041789cd6..c7b09701661c869d 100644 > --- a/tools/perf/util/Build > +++ b/tools/perf/util/Build > @@ -180,6 +180,7 @@ perf-$(CONFIG_LIBBABELTRACE) += data-convert-bt.o > perf-y += data-convert-json.o > > perf-y += scripting-engines/ > +perf-y += workqueue/ > > perf-$(CONFIG_ZLIB) += zlib.o > perf-$(CONFIG_LZMA) += lzma.o > diff --git a/tools/perf/util/workqueue/Build b/tools/perf/util/workqueue/Build > new file mode 100644 > index 0000000000000000..8b72a6cd4e2cba0d > --- /dev/null > +++ b/tools/perf/util/workqueue/Build > @@ -0,0 +1 @@ > +perf-y += threadpool.o > diff --git a/tools/perf/util/workqueue/threadpool.c b/tools/perf/util/workqueue/threadpool.c > new file mode 100644 > index 0000000000000000..70c67569f956a3e2 > --- /dev/null > +++ b/tools/perf/util/workqueue/threadpool.c > @@ -0,0 +1,175 @@ > +// SPDX-License-Identifier: GPL-2.0 > +#include <stdlib.h> > +#include <stdio.h> > +#include <unistd.h> > +#include <errno.h> > +#include <string.h> > +#include "debug.h" > +#include "asm/bug.h" > +#include "threadpool.h" > + > +enum threadpool_status { > + THREADPOOL_STATUS__STOPPED, /* no threads */ > + THREADPOOL_STATUS__ERROR, /* errors */ > + THREADPOOL_STATUS__MAX > +}; > + > +struct threadpool_struct {
Can this be just 'struct threadpool'? I think its descriptive enough:
> + int nr_threads; /* number of threads in the pool */ > + struct thread_struct *threads; /* array of threads in the pool */ > + struct task_struct *current_task; /* current executing function */ > + enum threadpool_status status; /* current status of the pool */ > +}; > + > +struct thread_struct { > + int idx; /* idx of thread in pool->threads */ > + pid_t tid; /* tid of thread */ > + struct threadpool_struct *pool; /* parent threadpool */ > + struct { > + int from[2]; /* messages from thread (acks) */ > + int to[2]; /* messages to thread (commands) */ > + } pipes; > +};
This one, since we have already a 'struct thread' in tools/perf, to represent a PERF_RECORD_FORK, perhaps we can call it 'struct threadpool_entry'?
> + > +/** > + * init_pipes - initialize all pipes of @thread > + */ > +static void init_pipes(struct thread_struct *thread) > +{ > + thread->pipes.from[0] = -1; > + thread->pipes.from[1] = -1; > + thread->pipes.to[0] = -1; > + thread->pipes.to[1] = -1; > +} > + > +/** > + * open_pipes - open all pipes of @thread > + */ > +static int open_pipes(struct thread_struct *thread)
Here please:
threadpool_entry__open_pipes()
Its longer, but helps with ctags/cscope navigation and we can go directly to it via:
:ta threadpool_entry__open_p<TAB>
While 'ta: open_pipes' may bo to various places where this idiom is used.
> +{ > + if (pipe(thread->pipes.from)) { > + pr_err("threadpool: failed to create comm pipe 'from': %s\n", > + strerror(errno)); > + return -ENOMEM; > + } > + > + if (pipe(thread->pipes.to)) { > + pr_err("threadpool: failed to create comm pipe 'to': %s\n", > + strerror(errno)); > + close(thread->pipes.from[0]); > + thread->pipes.from[0] = -1; > + close(thread->pipes.from[1]); > + thread->pipes.from[1] = -1; > + return -ENOMEM; > + } > + > + return 0; > +} > + > +/** > + * close_pipes - close all communication pipes of @thread > + */ > +static void close_pipes(struct thread_struct *thread) > +{ > + if (thread->pipes.from[0] != -1) { > + close(thread->pipes.from[0]); > + thread->pipes.from[0] = -1; > + } > + if (thread->pipes.from[1] != -1) { > + close(thread->pipes.from[1]); > + thread->pipes.from[1] = -1; > + } > + if (thread->pipes.to[0] != -1) { > + close(thread->pipes.to[0]); > + thread->pipes.to[0] = -1; > + } > + if (thread->pipes.to[1] != -1) { > + close(thread->pipes.to[1]); > + thread->pipes.to[1] = -1; > + } > +} > + > +/** > + * create_threadpool - create a fixed threadpool with @n_threads threads > + */ > +struct threadpool_struct *create_threadpool(int n_threads)
Is this already something the kernel has and thus we should keep the naming? I couldn't find it in the kernel, so please name it:
struct threadpool *threadpool__new(int nthreads)
> +{ > + int ret, t; > + struct threadpool_struct *pool = malloc(sizeof(*pool)); > + > + if (!pool) { > + pr_err("threadpool: cannot allocate pool: %s\n", > + strerror(errno));o
Humm, pr_err() at this level isn't appropriate, please make callers complain.
> + return NULL; > + } > + > + if (n_threads <= 0) { > + pr_err("threadpool: invalid number of threads: %d\n", > + n_threads);
pr_debug()
> + goto out_free_pool; > + } > + > + pool->nr_threads = n_threads; > + pool->current_task = NULL; > + > + pool->threads = malloc(n_threads * sizeof(*pool->threads)); > + if (!pool->threads) { > + pr_err("threadpool: cannot allocate threads: %s\n", > + strerror(errno)); > + goto out_free_pool; > + } > + > + for (t = 0; t < n_threads; t++) { > + pool->threads[t].idx = t; > + pool->threads[t].tid = -1; > + pool->threads[t].pool = pool; > + init_pipes(&pool->threads[t]); > + } > + > + for (t = 0; t < n_threads; t++) { > + ret = open_pipes(&pool->threads[t]); > + if (ret) > + goto out_close_pipes; > + } > + > + pool->status = THREADPOOL_STATUS__STOPPED; > + > + return pool; > + > +out_close_pipes: > + for (t = 0; t < n_threads; t++) > + close_pipes(&pool->threads[t]); > + > + free(pool->threads); > +out_free_pool: > + free(pool); > + return NULL;
Here we can use ERR_PTR()/PTR_ERR() to let the caller know what was the problem, i.e. we can ditch all the pr_err/pr_debug(), etc and instead have a threadpool__strerror(struct threadpool *pool, int err) like we have for 'struct evsel', please take a look at evsel__open_strerror().
> +} > + > +/** > + * destroy_threadpool - free the @pool and all its resources > + */ > +void destroy_threadpool(struct threadpool_struct *pool)
void threadpool__delete(struct threadpool *pool) > +{ > + int t; > + > + if (!pool) > + return; > + > + WARN_ON(pool->status != THREADPOOL_STATUS__STOPPED > + && pool->status != THREADPOOL_STATUS__ERROR); > + > + for (t = 0; t < pool->nr_threads; t++) > + close_pipes(&pool->threads[t]);
reset pool->threads[t] to -1
> + > + free(pool->threads);
zfree
> + free(pool); > +} > + > +/** > + * threadpool_size - get number of threads in the threadpool > + */ > +int threadpool_size(struct threadpool_struct *pool)
threadpool__size()
> +{ > + return pool->nr_threads; > +} > diff --git a/tools/perf/util/workqueue/threadpool.h b/tools/perf/util/workqueue/threadpool.h > new file mode 100644 > index 0000000000000000..2b9388c768a0b588 > --- /dev/null > +++ b/tools/perf/util/workqueue/threadpool.h > @@ -0,0 +1,19 @@ > +/* SPDX-License-Identifier: GPL-2.0 */ > +#ifndef __WORKQUEUE_THREADPOOL_H > +#define __WORKQUEUE_THREADPOOL_H > + > +struct threadpool_struct; > +struct task_struct; > + > +typedef void (*task_func_t)(int tidx, struct task_struct *task); > + > +struct task_struct { > + task_func_t fn; > +}; > + > +extern struct threadpool_struct *create_threadpool(int n_threads); > +extern void destroy_threadpool(struct threadpool_struct *pool); > + > +extern int threadpool_size(struct threadpool_struct *pool); > + > +#endif /* __WORKQUEUE_THREADPOOL_H */ > -- > 2.31.1 >
--
- Arnaldo
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