Re: [PATCH v5 07/10] perf record: implement -z,--compression_level=n option and compression

Jiri Olsa
2019-03-07T12:14:34Z

On Thu, Mar 07, 2019 at 11:39:46AM +0300, Alexey Budankov wrote:
>
> On 05.03.2019 15:25, Jiri Olsa wrote:
> > On Fri, Mar 01, 2019 at 06:58:32PM +0300, Alexey Budankov wrote:
> >
> > SNIP
> >
> >>
> >> /*
> >> * Increment md->refcount to guard md->data[idx] buffer
> >> @@ -350,7 +357,7 @@ int perf_mmap__aio_push(struct perf_mmap *md, void *to, int idx,
> >> md->prev = head;
> >> perf_mmap__consume(md);
> >>
> >> - rc = push(to, &md->aio.cblocks[idx], md->aio.data[idx], size0 + size, *off);
> >> + rc = push(to, md->aio.data[idx], size0 + size, *off, &md->aio.cblocks[idx]);
> >> if (!rc) {
> >> *off += size0 + size;
> >> } else {
> >> @@ -556,13 +563,15 @@ int perf_mmap__read_init(struct perf_mmap *map)
> >> }
> >>
> >> int perf_mmap__push(struct perf_mmap *md, void *to,
> >> - int push(struct perf_mmap *map, void *to, void *buf, size_t size))
> >> + int push(struct perf_mmap *map, void *to, void *buf, size_t size),
> >> + perf_mmap__compress_fn_t compress, void *comp_data)
> >> {
> >> u64 head = perf_mmap__read_head(md);
> >> unsigned char *data = md->base + page_size;
> >> unsigned long size;
> >> void *buf;
> >> int rc = 0;
> >> + size_t mmap_len = perf_mmap__mmap_len(md);
> >>
> >> rc = perf_mmap__read_init(md);
> >> if (rc < 0)
> >> @@ -574,7 +583,10 @@ int perf_mmap__push(struct perf_mmap *md, void *to,
> >> buf = &data[md->start & md->mask];
> >> size = md->mask + 1 - (md->start & md->mask);
> >> md->start += size;
> >> -
> >> + if (compress) {
> >> + size = compress(comp_data, md->data, mmap_len, buf, size);
> >> + buf = md->data;
> >> + }
> >> if (push(md, to, buf, size) < 0) {
> >> rc = -1;
> >> goto out;
> >
> > when we discussed the compress callback should be another layer
> > in perf_mmap__push I was thinking more of the layered/fifo design,
> > like:
> >
> > normaly we call:
> >
> > perf_mmap__push(... push = record__pushfn ...)
> > -> reads mmap data and calls push(data), which translates as:
> >
> > record__pushfn(data);
> > - which stores the data
> >
> >
> > for compressed it'd be:
> >
> > perf_mmap__push(... push = compressed_push ...)
> >
> > -> reads mmap data and calls push(data), which translates as:
> >
> > compressed_push(data)
> > -> reads data, compresses them and calls, next push callback in line:
> >
> > record__pushfn(data)
> > - which stores the data
> >
> >
> > there'd need to be the logic for compressed_push to
> > remember the 'next push' function
>
> That is suboptimal for AIO. Also compression is an independent operation that
> could be applied on any of push stages you mean.

not sure what you mean by suboptimal, but I think
that it can still happen in subsequent push callback

>
> >
> > but I think this was the original idea behind the
> > perf_mmap__push -> it gets the data and pushes them for
> > the next processing.. it should stay as simple as that
>
> Agree on keeping simplicity and, at the moment, there is no any push to the next
> processing in the code so provided implementation fits as for serial as for AIO
> at the same time sticking to simplicity as much as possibly. If you see something
> that would fit better please speak up and share.

I have to insist that perf_mmap__push stays untouched
and we do other processing in the push callbacks

jirka