Re: [RFC PATCH] perf, bpf: Retain kernel executable code in memory to aid Intel PT tracing

2019-02-11 Thread Adrian Hunter
On 11/02/19 10:18 AM, Alexei Starovoitov wrote: > On Mon, Feb 11, 2019 at 09:54:01AM +0200, Adrian Hunter wrote: >> >> Which is not really a real use-case. > .. >>> perf analysis with PT becomes inaccurate and main goal >>> of retaining accurate instruction info is not achieved. >> >> For the major

Re: [RFC PATCH] perf, bpf: Retain kernel executable code in memory to aid Intel PT tracing

2019-02-11 Thread Alexei Starovoitov
On Mon, Feb 11, 2019 at 09:54:01AM +0200, Adrian Hunter wrote: > > Which is not really a real use-case. .. > > perf analysis with PT becomes inaccurate and main goal > > of retaining accurate instruction info is not achieved. > > For the majority of real use-cases, yes it is. In our fleet not a

Re: [RFC PATCH] perf, bpf: Retain kernel executable code in memory to aid Intel PT tracing

2019-02-10 Thread Adrian Hunter
On 9/02/19 1:29 AM, Alexei Starovoitov wrote: > On Thu, Feb 07, 2019 at 01:19:01PM +0200, Adrian Hunter wrote: >> Subject to memory pressure and other limits, retain executable code, such >> as JIT-compiled bpf, in memory instead of freeing it immediately it is no >> longer needed for execution. >>

Re: [RFC PATCH] perf, bpf: Retain kernel executable code in memory to aid Intel PT tracing

2019-02-08 Thread Alexei Starovoitov
On Thu, Feb 07, 2019 at 01:19:01PM +0200, Adrian Hunter wrote: > Subject to memory pressure and other limits, retain executable code, such > as JIT-compiled bpf, in memory instead of freeing it immediately it is no > longer needed for execution. > > While perf is primarily aimed at statistical ana