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Peter Anvin" Cc: zhiquan1.li@intel.com, Kristen Carlson Accardi , Sean Christopherson Subject: [PATCH v2 01/18] x86/sgx: Call cond_resched() at the end of sgx_reclaim_pages() Date: Fri, 2 Dec 2022 10:36:37 -0800 Message-Id: <20221202183655.3767674-2-kristen@linux.intel.com> X-Mailer: git-send-email 2.38.1 In-Reply-To: <20221202183655.3767674-1-kristen@linux.intel.com> References: <20221202183655.3767674-1-kristen@linux.intel.com> MIME-Version: 1.0 Content-Transfer-Encoding: 8bit Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org From: Sean Christopherson In order to avoid repetition of cond_resched() in ksgxd() and sgx_alloc_epc_page(), move the invocation of post-reclaim cond_resched() inside sgx_reclaim_pages(). Except in the case of sgx_reclaim_direct(), sgx_reclaim_pages() is always called in a loop and is always followed by a call to cond_resched(). This will hold true for the EPC cgroup as well, which adds even more calls to sgx_reclaim_pages() and thus cond_resched(). Calls to sgx_reclaim_direct() may be performance sensitive. Allow sgx_reclaim_direct() to avoid the cond_resched() call by moving the original sgx_reclaim_pages() call to __sgx_reclaim_pages() and then have sgx_reclaim_pages() become a wrapper around that call with a cond_resched(). Signed-off-by: Sean Christopherson Signed-off-by: Kristen Carlson Accardi Cc: Sean Christopherson --- arch/x86/kernel/cpu/sgx/main.c | 17 +++++++++++------ 1 file changed, 11 insertions(+), 6 deletions(-) diff --git a/arch/x86/kernel/cpu/sgx/main.c b/arch/x86/kernel/cpu/sgx/main.c index 160c8dbee0ab..ffce6fc70a1f 100644 --- a/arch/x86/kernel/cpu/sgx/main.c +++ b/arch/x86/kernel/cpu/sgx/main.c @@ -287,7 +287,7 @@ static void sgx_reclaimer_write(struct sgx_epc_page *epc_page, * problematic as it would increase the lock contention too much, which would * halt forward progress. */ -static void sgx_reclaim_pages(void) +static void __sgx_reclaim_pages(void) { struct sgx_epc_page *chunk[SGX_NR_TO_SCAN]; struct sgx_backing backing[SGX_NR_TO_SCAN]; @@ -369,6 +369,12 @@ static void sgx_reclaim_pages(void) } } +static void sgx_reclaim_pages(void) +{ + __sgx_reclaim_pages(); + cond_resched(); +} + static bool sgx_should_reclaim(unsigned long watermark) { return atomic_long_read(&sgx_nr_free_pages) < watermark && @@ -378,12 +384,14 @@ static bool sgx_should_reclaim(unsigned long watermark) /* * sgx_reclaim_direct() should be called (without enclave's mutex held) * in locations where SGX memory resources might be low and might be - * needed in order to make forward progress. + * needed in order to make forward progress. This call to + * __sgx_reclaim_pages() avoids the cond_resched() in sgx_reclaim_pages() + * to improve performance. */ void sgx_reclaim_direct(void) { if (sgx_should_reclaim(SGX_NR_LOW_PAGES)) - sgx_reclaim_pages(); + __sgx_reclaim_pages(); } static int ksgxd(void *p) @@ -410,8 +418,6 @@ static int ksgxd(void *p) if (sgx_should_reclaim(SGX_NR_HIGH_PAGES)) sgx_reclaim_pages(); - - cond_resched(); } return 0; @@ -582,7 +588,6 @@ struct sgx_epc_page *sgx_alloc_epc_page(void *owner, bool reclaim) } sgx_reclaim_pages(); - cond_resched(); } if (sgx_should_reclaim(SGX_NR_LOW_PAGES)) -- 2.38.1