On Mon, Apr 4, 2022 at 1:03 AM Tzvetomir Stoyanov <tz.stoyanov@xxxxxxxxx> wrote: > > On Mon, Apr 4, 2022 at 7:41 AM Tzvetomir Stoyanov <tz.stoyanov@xxxxxxxxx> wrote: > > > > On Sun, Apr 3, 2022 at 5:56 PM Joel Fernandes <joel@xxxxxxxxxxxxxxxxx> wrote: > > > > > > On Fri, Apr 01, 2022 at 07:06:29PM -0400, Steven Rostedt wrote: > > > > On Fri, 1 Apr 2022 15:50:10 -0400 > > > > Joel Fernandes <joel@xxxxxxxxxxxxxxxxx> wrote: > > > > > > > > > export TRACECMD_TEMPDIR="/data" > > > > > > > > > > That’s fair. What about using memfd for this, do you feel that’s > > > > > reasonable? I have not yet measured how big this file gets but if it’s > > > > > small enough that might work too. > > > > > > > > Is this a separate question? That is, do you mean using the above > > > > environment variable *and* then use memfd? > > > > > > > > I believe that the cache is used for passing the compressed data from the > > > > guest to the host. I don't think it will be more than one compressed chunk. > > > > > > > > But Tzvetomir would know better. > > > > > > Hey Steve, > > > No its the same question. Instead of temp file, I was proposing in-memory > > > file using memfd_create(2), that way no hassle as long as the file is not too > > > huge. > > > > > > > Hi Joel, > > That cache file is used for constructing the trace meta-data on the > > guest, before sending it to the host. Usually it is compressed, but it > > could be uncompressed in some cases (depending on the configuration) - > > and in that case it can grow up to a few megabytes. Using memfd is ok > > in most cases, but I'm wondering in the worst case - these few > > megabytes could be a problem, especially if the guest runs with a > > minimum amount of memory. > > > > Can you check that file size on your Android setup with that command, > it will force to not use compression on the guest trace file: > trace-cmd <host trace options> -A <guest> <guest trace options> > --file-version 7 --compression none The file grows to 5.3MB with this. Is this really the common case though? If not, I would still prefer memfd tbh. Is that Ok with you? Thanks, - Joel
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