From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from out-186.mta1.migadu.com (out-186.mta1.migadu.com [95.215.58.186]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id DF2E763B9 for ; Thu, 13 Mar 2025 17:03:34 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=95.215.58.186 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1741885416; cv=none; b=dRNlHejVnH/OqUsdgKFoHXtfM4rjCeZoJUQn3OD+/2e5JSXo22Kk9BRfSEdcxAWjp0HDL48Uavf5yEEGZVdHCvV0il4LLkCkpgl6HDZxuqNFC7lc04KpymAtp2pXK1tKZi0AkWpgj/Zgf8yavt3nusY/DGec00qwcBMT3iy9tNA= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1741885416; c=relaxed/simple; bh=rHd91RDVZblAGkL9tzN0XV7AHBKS9VBYY+yYlPibRN0=; h=Message-ID:Date:MIME-Version:Subject:To:Cc:References:From: In-Reply-To:Content-Type; b=KM7K8u3jbi/Jdb+kVIMktO0nbebwv7x/xzYKVRBwr6ozN/qk+CJNYCLeC0mocRFbMTegUJaesms5lgzCS3sgdNoJlO6GqLkdWVO6mn5gls/hZF70YY8R9Q8NevV7jkRgRVLkz/5/vOpGJyPC1I66zSF/oqFvWo93cTxpBDLQs4c= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=linux.dev; spf=pass smtp.mailfrom=linux.dev; dkim=pass (1024-bit key) header.d=linux.dev header.i=@linux.dev header.b=vIhwNBwy; arc=none smtp.client-ip=95.215.58.186 Authentication-Results: smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=linux.dev Authentication-Results: smtp.subspace.kernel.org; spf=pass smtp.mailfrom=linux.dev Authentication-Results: smtp.subspace.kernel.org; dkim=pass (1024-bit key) header.d=linux.dev header.i=@linux.dev header.b="vIhwNBwy" Message-ID: <87b67a79-d97e-4f81-9bf2-aa34d613b5bf@linux.dev> DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=linux.dev; s=key1; t=1741885402; h=from:from:reply-to:subject:subject:date:date:message-id:message-id: to:to:cc:cc:mime-version:mime-version:content-type:content-type: content-transfer-encoding:content-transfer-encoding: in-reply-to:in-reply-to:references:references; bh=Wcq4k6tGNSE5Yn0/7eafZbLAzGJWuw56xZay697EIM4=; b=vIhwNBwyHcr4PEAJ+pjazisIdLm3yG/A5zwei8NPmLqDjQ6IOTHy01O/9FtFgD6hh3KdfR +7fCO5ZSKg4n0VsNshOry0CZdgerepmy+4FyKS8bDo2lstBFkYTAa/fXRAaJlV8/jMZwbn bUTKZu4eXRYgg2qhMFH5982CoukTRy4= Date: Fri, 14 Mar 2025 01:03:13 +0800 Precedence: bulk X-Mailing-List: linux-perf-users@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Subject: Re: [PATCH linux-next] perf/ring_buffer: Add EPOLLRDNORM flag for poll To: Ingo Molnar Cc: peterz@infradead.org, mingo@redhat.com, acme@kernel.org, namhyung@kernel.org, mark.rutland@arm.com, alexander.shishkin@linux.intel.com, jolsa@kernel.org, irogers@google.com, adrian.hunter@intel.com, kan.liang@linux.intel.com, linux-perf-users@vger.kernel.org, linux-kernel@vger.kernel.org References: <20250313051047.2436098-1-chen.dylane@linux.dev> X-Report-Abuse: Please report any abuse attempt to abuse@migadu.com and include these headers. From: Tao Chen In-Reply-To: Content-Type: text/plain; charset=UTF-8; format=flowed Content-Transfer-Encoding: 8bit X-Migadu-Flow: FLOW_OUT 在 2025/3/13 18:05, Ingo Molnar 写道: > > * Tao Chen wrote: > >> The poll man page says POLLRDNORM is equivalent to POLLIN, >> so add EPOLLRDNORM here. >> >> Signed-off-by: Tao Chen >> --- >> kernel/events/ring_buffer.c | 2 +- >> 1 file changed, 1 insertion(+), 1 deletion(-) >> >> diff --git a/kernel/events/ring_buffer.c b/kernel/events/ring_buffer.c >> index 59a52b1a1..5130b119d 100644 >> --- a/kernel/events/ring_buffer.c >> +++ b/kernel/events/ring_buffer.c >> @@ -19,7 +19,7 @@ >> >> static void perf_output_wakeup(struct perf_output_handle *handle) >> { >> - atomic_set(&handle->rb->poll, EPOLLIN); >> + atomic_set(&handle->rb->poll, EPOLLIN | EPOLLRDNORM); > > So what does EPOLLRDNORM mean to begin with? There doesn't seem to be > separate/specific handling of it anywhere in the kernel that I can > see... > It seems that if user set pollfd with POLLRDNORM, perf_poll will not return until timeout even if perf_output_wakeup called, whereas POLLIN returns. > Thanks, > > Ingo -- Best Regards Tao Chen