From: Andrew Jones <ajones@ventanamicro.com> To: Atish Patra <atishp@rivosinc.com> Cc: linux-kernel@vger.kernel.org, Palmer Dabbelt <palmer@rivosinc.com>, Anup Patel <anup@brainfault.org>, Conor Dooley <conor.dooley@microchip.com>, Ajay Kaher <akaher@vmware.com>, Alexandre Ghiti <alexghiti@rivosinc.com>, Alexey Makhalov <amakhalov@vmware.com>, Juergen Gross <jgross@suse.com>, kvm-riscv@lists.infradead.org, kvm@vger.kernel.org, linux-kselftest@vger.kernel.org, linux-riscv@lists.infradead.org, Mark Rutland <mark.rutland@arm.com>, Palmer Dabbelt <palmer@dabbelt.com>, Paolo Bonzini <pbonzini@redhat.com>, Paul Walmsley <paul.walmsley@sifive.com>, Shuah Khan <shuah@kernel.org>, virtualization@lists.linux.dev, VMware PV-Drivers Reviewers <pv-drivers@vmware.com>, Will Deacon <will@kernel.org>, x86@kernel.org Subject: Re: [PATCH v5 06/22] drivers/perf: riscv: Implement SBI PMU snapshot function Date: Thu, 11 Apr 2024 09:45:19 +0200 [thread overview] Message-ID: <20240411-688dc97b08bb3b63511dcf6e@orel> (raw) In-Reply-To: <170cc87a-5b55-45be-a0de-213aabd852dc@rivosinc.com> On Wed, Apr 10, 2024 at 03:29:21PM -0700, Atish Patra wrote: > On 4/4/24 04:52, Andrew Jones wrote: > > On Wed, Apr 03, 2024 at 01:04:35AM -0700, Atish Patra wrote: ... > > > +static int pmu_sbi_snapshot_disable(void) > > > +{ > > > + struct sbiret ret; > > > + > > > + ret = sbi_ecall(SBI_EXT_PMU, SBI_EXT_PMU_SNAPSHOT_SET_SHMEM, -1, > > > + -1, 0, 0, 0, 0); > > > + if (ret.error) { > > > + pr_warn("failed to disable snapshot shared memory\n"); > > > + return sbi_err_map_linux_errno(ret.error); > > > + } > > > > Also need to set snapshot_set_done to false, but I'm not yet convinced > > Done. > > > that we need snapshot_set_done, especially if we don't allow > > snapshot_addr_phys to be zero, since zero can then mean set-not-done, > > but ~0UL is probably a better invalid physical address choice than zero. > > > > Agreed. But I don't see any benefit either way. snapshot_set_done is just > more explicit way of doing the same thing without interpreting what zero > means. > > If you think there is a benefit or you feel storngly about it, I can change > it you suggested approach. > I don't have a strong opinion on it. I'm just reluctant to add redundant state, not only because it increases size, but also because we have to keep track of it, like in the example above, where we needed to remember to reset the extra state to false. Of course, giving invalid addresses additional meanings also comes with its own code maintenance trade-offs, so either way... Thanks, drew
WARNING: multiple messages have this Message-ID (diff)
From: Andrew Jones <ajones@ventanamicro.com> To: Atish Patra <atishp@rivosinc.com> Cc: linux-kernel@vger.kernel.org, Palmer Dabbelt <palmer@rivosinc.com>, Anup Patel <anup@brainfault.org>, Conor Dooley <conor.dooley@microchip.com>, Ajay Kaher <akaher@vmware.com>, Alexandre Ghiti <alexghiti@rivosinc.com>, Alexey Makhalov <amakhalov@vmware.com>, Juergen Gross <jgross@suse.com>, kvm-riscv@lists.infradead.org, kvm@vger.kernel.org, linux-kselftest@vger.kernel.org, linux-riscv@lists.infradead.org, Mark Rutland <mark.rutland@arm.com>, Palmer Dabbelt <palmer@dabbelt.com>, Paolo Bonzini <pbonzini@redhat.com>, Paul Walmsley <paul.walmsley@sifive.com>, Shuah Khan <shuah@kernel.org>, virtualization@lists.linux.dev, VMware PV-Drivers Reviewers <pv-drivers@vmware.com>, Will Deacon <will@kernel.org>, x86@kernel.org Subject: Re: [PATCH v5 06/22] drivers/perf: riscv: Implement SBI PMU snapshot function Date: Thu, 11 Apr 2024 09:45:19 +0200 [thread overview] Message-ID: <20240411-688dc97b08bb3b63511dcf6e@orel> (raw) In-Reply-To: <170cc87a-5b55-45be-a0de-213aabd852dc@rivosinc.com> On Wed, Apr 10, 2024 at 03:29:21PM -0700, Atish Patra wrote: > On 4/4/24 04:52, Andrew Jones wrote: > > On Wed, Apr 03, 2024 at 01:04:35AM -0700, Atish Patra wrote: ... > > > +static int pmu_sbi_snapshot_disable(void) > > > +{ > > > + struct sbiret ret; > > > + > > > + ret = sbi_ecall(SBI_EXT_PMU, SBI_EXT_PMU_SNAPSHOT_SET_SHMEM, -1, > > > + -1, 0, 0, 0, 0); > > > + if (ret.error) { > > > + pr_warn("failed to disable snapshot shared memory\n"); > > > + return sbi_err_map_linux_errno(ret.error); > > > + } > > > > Also need to set snapshot_set_done to false, but I'm not yet convinced > > Done. > > > that we need snapshot_set_done, especially if we don't allow > > snapshot_addr_phys to be zero, since zero can then mean set-not-done, > > but ~0UL is probably a better invalid physical address choice than zero. > > > > Agreed. But I don't see any benefit either way. snapshot_set_done is just > more explicit way of doing the same thing without interpreting what zero > means. > > If you think there is a benefit or you feel storngly about it, I can change > it you suggested approach. > I don't have a strong opinion on it. I'm just reluctant to add redundant state, not only because it increases size, but also because we have to keep track of it, like in the example above, where we needed to remember to reset the extra state to false. Of course, giving invalid addresses additional meanings also comes with its own code maintenance trade-offs, so either way... Thanks, drew _______________________________________________ linux-riscv mailing list linux-riscv@lists.infradead.org http://lists.infradead.org/mailman/listinfo/linux-riscv
next prev parent reply other threads:[~2024-04-11 7:45 UTC|newest] Thread overview: 117+ messages / expand[flat|nested] mbox.gz Atom feed top 2024-04-03 8:04 [PATCH v5 00/22] RISC-V SBI v2.0 PMU improvements and Perf sampling in KVM guest Atish Patra 2024-04-03 8:04 ` Atish Patra 2024-04-03 8:04 ` [PATCH v5 01/22] RISC-V: Fix the typo in Scountovf CSR name Atish Patra 2024-04-03 8:04 ` Atish Patra 2024-04-04 10:56 ` Andrew Jones 2024-04-04 10:56 ` Andrew Jones 2024-04-03 8:04 ` [PATCH v5 02/22] RISC-V: Add FIRMWARE_READ_HI definition Atish Patra 2024-04-03 8:04 ` Atish Patra 2024-04-04 10:57 ` Andrew Jones 2024-04-04 10:57 ` Andrew Jones 2024-04-03 8:04 ` [PATCH v5 03/22] drivers/perf: riscv: Read upper bits of a firmware counter Atish Patra 2024-04-03 8:04 ` Atish Patra 2024-04-04 11:02 ` Andrew Jones 2024-04-04 11:02 ` Andrew Jones 2024-04-09 0:04 ` Atish Patra 2024-04-09 0:04 ` Atish Patra 2024-04-03 8:04 ` [PATCH v5 04/22] drivers/perf: riscv: Use BIT macro for shifting operations Atish Patra 2024-04-03 8:04 ` Atish Patra 2024-04-03 15:57 ` unsubscribe jonathan.oleson 2024-04-04 11:08 ` [PATCH v5 04/22] drivers/perf: riscv: Use BIT macro for shifting operations Andrew Jones 2024-04-04 11:08 ` Andrew Jones 2024-04-09 0:20 ` Atish Patra 2024-04-09 0:20 ` Atish Patra 2024-04-03 8:04 ` [PATCH v5 05/22] RISC-V: Add SBI PMU snapshot definitions Atish Patra 2024-04-03 8:04 ` Atish Patra 2024-04-04 11:14 ` Andrew Jones 2024-04-04 11:14 ` Andrew Jones 2024-04-03 8:04 ` [PATCH v5 06/22] drivers/perf: riscv: Implement SBI PMU snapshot function Atish Patra 2024-04-03 8:04 ` Atish Patra 2024-04-04 11:52 ` Andrew Jones 2024-04-04 11:52 ` Andrew Jones 2024-04-10 22:29 ` Atish Patra 2024-04-10 22:29 ` Atish Patra 2024-04-11 7:45 ` Andrew Jones [this message] 2024-04-11 7:45 ` Andrew Jones 2024-04-04 12:01 ` Andrew Jones 2024-04-04 12:01 ` Andrew Jones 2024-04-09 0:21 ` Atish Patra 2024-04-09 0:21 ` Atish Patra 2024-04-03 8:04 ` [PATCH v5 07/22] drivers/perf: riscv: Fix counter mask iteration for RV32 Atish Patra 2024-04-03 8:04 ` Atish Patra 2024-04-04 11:55 ` Andrew Jones 2024-04-04 11:55 ` Andrew Jones 2024-04-03 8:04 ` [PATCH v5 08/22] RISC-V: KVM: Fix the initial sample period value Atish Patra 2024-04-03 8:04 ` Atish Patra 2024-04-04 11:57 ` Andrew Jones 2024-04-04 11:57 ` Andrew Jones 2024-04-03 8:04 ` [PATCH v5 09/22] RISC-V: KVM: Rename the SBI_STA_SHMEM_DISABLE to a generic name Atish Patra 2024-04-03 8:04 ` Atish Patra 2024-04-04 11:59 ` Andrew Jones 2024-04-04 11:59 ` Andrew Jones 2024-04-03 8:04 ` [PATCH v5 10/22] RISC-V: KVM: No need to update the counter value during reset Atish Patra 2024-04-03 8:04 ` Atish Patra 2024-04-03 8:04 ` [PATCH v5 11/22] RISC-V: KVM: No need to exit to the user space if perf event failed Atish Patra 2024-04-03 8:04 ` Atish Patra 2024-04-04 12:19 ` Andrew Jones 2024-04-04 12:19 ` Andrew Jones 2024-04-03 8:04 ` [PATCH v5 12/22] RISC-V: KVM: Implement SBI PMU Snapshot feature Atish Patra 2024-04-03 8:04 ` Atish Patra 2024-04-05 11:23 ` Andrew Jones 2024-04-05 11:23 ` Andrew Jones 2024-04-09 0:33 ` Atish Patra 2024-04-09 0:33 ` Atish Patra 2024-04-03 8:04 ` [PATCH v5 13/22] RISC-V: KVM: Add perf sampling support for guests Atish Patra 2024-04-03 8:04 ` Atish Patra 2024-04-05 11:36 ` Andrew Jones 2024-04-05 11:36 ` Andrew Jones 2024-04-03 8:04 ` [PATCH v5 14/22] RISC-V: KVM: Support 64 bit firmware counters on RV32 Atish Patra 2024-04-03 8:04 ` Atish Patra 2024-04-05 12:10 ` Andrew Jones 2024-04-05 12:10 ` Andrew Jones 2024-04-03 8:04 ` [PATCH v5 15/22] RISC-V: KVM: Improve firmware counter read function Atish Patra 2024-04-03 8:04 ` Atish Patra 2024-04-05 12:12 ` Andrew Jones 2024-04-05 12:12 ` Andrew Jones 2024-04-03 8:04 ` [PATCH v5 16/22] KVM: riscv: selftests: Move sbi definitions to its own header file Atish Patra 2024-04-03 8:04 ` Atish Patra 2024-04-05 12:16 ` Andrew Jones 2024-04-05 12:16 ` Andrew Jones 2024-04-03 8:04 ` [PATCH v5 17/22] KVM: riscv: selftests: Add helper functions for extension checks Atish Patra 2024-04-03 8:04 ` Atish Patra 2024-04-05 12:17 ` Andrew Jones 2024-04-05 12:17 ` Andrew Jones 2024-04-03 8:04 ` [PATCH v5 18/22] KVM: riscv: selftests: Add Sscofpmf to get-reg-list test Atish Patra 2024-04-03 8:04 ` Atish Patra 2024-04-03 8:04 ` [PATCH v5 19/22] KVM: riscv: selftests: Add SBI PMU extension definitions Atish Patra 2024-04-03 8:04 ` Atish Patra 2024-04-05 12:20 ` Andrew Jones 2024-04-05 12:20 ` Andrew Jones 2024-04-03 8:04 ` [PATCH v5 20/22] KVM: riscv: selftests: Add SBI PMU selftest Atish Patra 2024-04-03 8:04 ` Atish Patra 2024-04-05 12:50 ` Andrew Jones 2024-04-05 12:50 ` Andrew Jones 2024-04-09 0:37 ` Atish Patra 2024-04-09 0:37 ` Atish Patra 2024-04-09 8:01 ` Andrew Jones 2024-04-09 8:01 ` Andrew Jones 2024-04-09 22:11 ` Atish Kumar Patra 2024-04-09 22:11 ` Atish Kumar Patra 2024-04-03 8:04 ` [PATCH v5 21/22] KVM: riscv: selftests: Add a test for PMU snapshot functionality Atish Patra 2024-04-03 8:04 ` Atish Patra 2024-04-05 13:11 ` Andrew Jones 2024-04-05 13:11 ` Andrew Jones 2024-04-09 22:52 ` Atish Patra 2024-04-09 22:52 ` Atish Patra 2024-04-10 7:10 ` Andrew Jones 2024-04-10 7:10 ` Andrew Jones 2024-04-10 7:28 ` Atish Patra 2024-04-10 7:28 ` Atish Patra 2024-04-10 7:54 ` Andrew Jones 2024-04-10 7:54 ` Andrew Jones 2024-04-03 8:04 ` [PATCH v5 22/22] KVM: riscv: selftests: Add a test for counter overflow Atish Patra 2024-04-03 8:04 ` Atish Patra 2024-04-05 13:23 ` Andrew Jones 2024-04-05 13:23 ` Andrew Jones 2024-04-09 23:47 ` Atish Patra 2024-04-09 23:47 ` Atish Patra
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