From: Jakub Sitnicki <jakub@cloudflare.com>
To: Yaniv Agman <yanivagman@gmail.com>
Cc: Martin KaFai Lau <martin.lau@linux.dev>,
bpf <bpf@vger.kernel.org>, Yonghong Song <yhs@meta.com>
Subject: Re: Are BPF programs preemptible?
Date: Mon, 23 Jan 2023 22:22:27 +0100 [thread overview]
Message-ID: <87k01dvt83.fsf@cloudflare.com> (raw)
In-Reply-To: <CAMy7=ZWi35SKj9rcKwj0eyH+xY8ZBgiX_vpF=mydxFDahK6trg@mail.gmail.com>
On Mon, Jan 23, 2023 at 11:01 PM +02, Yaniv Agman wrote:
> בתאריך יום ב׳, 23 בינו׳ 2023 ב-22:06 מאת Martin KaFai Lau
> <martin.lau@linux.dev>:
>>
>> On 1/23/23 9:32 AM, Yaniv Agman wrote:
>> >>> interrupted the first one. But even then, I will need to find a way to
>> >>> know if my program currently interrupts the run of another program -
>> >>> is there a way to do that?
>> May be a percpu atomic counter to see if the bpf prog has been re-entered on the
>> same cpu.
>
> Not sure I understand how this will help. If I want to save local
> program data on a percpu map and I see that the counter is bigger then
> zero, should I ignore the event?
map_update w/ BPF_F_LOCK disables preemption, if you're after updating
an entry atomically. But it can't be used with PERCPU maps today.
Perhaps that's needed now too.
next prev parent reply other threads:[~2023-01-23 21:25 UTC|newest]
Thread overview: 21+ messages / expand[flat|nested] mbox.gz Atom feed top
2023-01-23 9:21 Are BPF programs preemptible? Yaniv Agman
2023-01-23 10:46 ` Jakub Sitnicki
2023-01-23 12:30 ` Yaniv Agman
2023-01-23 17:02 ` Yonghong Song
2023-01-23 17:32 ` Yaniv Agman
2023-01-23 20:06 ` Martin KaFai Lau
2023-01-23 21:01 ` Yaniv Agman
2023-01-23 21:22 ` Jakub Sitnicki [this message]
2023-01-23 21:56 ` Yaniv Agman
2023-01-24 12:30 ` Alexei Starovoitov
2023-01-24 15:47 ` Yaniv Agman
2023-01-24 17:24 ` Alexei Starovoitov
2023-01-24 17:38 ` Yaniv Agman
2023-01-25 0:04 ` Alexei Starovoitov
2023-01-25 16:39 ` Yaniv Agman
2023-01-25 18:52 ` Alexei Starovoitov
2023-01-25 19:59 ` Yaniv Agman
2023-01-26 2:22 ` Alexei Starovoitov
2023-01-26 6:59 ` Yaniv Agman
2023-01-26 15:29 ` Alexei Starovoitov
2023-01-26 17:51 ` Yaniv Agman
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