From: William Cohen <wcohen@redhat.com>
To: Serhei Makarov <serhei@fastmail.com>, systemtap@sourceware.org
Subject: Re: stap/eBPF language features brainstorm
Date: Thu, 19 Jul 2018 15:27:00 -0000 [thread overview]
Message-ID: <01c4f735-68b0-7d0b-11bf-0c89523839ca@redhat.com> (raw)
In-Reply-To: <1531340017.1855006.1437712520.41D1C30F@webmail.messagingengine.com>
On 07/11/2018 04:13 PM, Serhei Makarov wrote:
> Some very rough ideas on how to jam further desirable SystemTap language features into the constraints of eBPF. The goal isn't for total feature-parity with the kernel backend (that's not feasible) but for the restrictions to be clear and understandable, e.g.:
...
> - Certain operations (e.g. foreach) can only be done in userspace. It's clearly documented which probes run in userspace (e.g. begin, end, selected ?timer probes).
A number of the systemtap script have idioms like the following from iotop.stp:
global io_stat,device
global read_bytes,write_bytes
...
probe timer.ms(5000) {
/* write out data */
/* clear data */
delete io_stat
delete device
read_bytes = 0
write_bytes = 0
}
Is there some way to clear out all the previous entries in the bpf map from the timer probe?
-Will
next prev parent reply other threads:[~2018-07-19 15:27 UTC|newest]
Thread overview: 5+ messages / expand[flat|nested] mbox.gz Atom feed top
2018-07-11 20:13 Serhei Makarov
2018-07-12 15:47 ` Serhei Makarov
2018-07-19 15:27 ` William Cohen [this message]
2018-07-19 17:32 ` Serhei Makarov
2018-07-19 17:56 ` William Cohen
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