From: Sukadev Bhattiprolu <sukadev@linux.vnet.ibm.com>
To: Michael Ellerman <mpe@ellerman.id.au>
Cc: Benjamin Herrenschmidt <benh@kernel.crashing.org>,
mikey@neuling.org, hbabu@us.ibm.com, nicholas.piggin@gmail.com,
linuxppc-dev@ozlabs.org, <linux-kernel@vger.kernel.org>
Subject: [PATCH v3 04/18] powerpc/vas: Drop poll_window_cast_out().
Date: Tue, 7 Nov 2017 18:23:44 -0800 [thread overview]
Message-ID: <1510107838-15181-5-git-send-email-sukadev@linux.vnet.ibm.com> (raw)
In-Reply-To: <1510107838-15181-1-git-send-email-sukadev@linux.vnet.ibm.com>
Polling for window cast out is listed in the spec, but turns out that
it is not strictly necessary and slows down window close. Making it a
stub for now.
Signed-off-by: Sukadev Bhattiprolu <sukadev@linux.vnet.ibm.com>
---
arch/powerpc/platforms/powernv/vas-window.c | 34 ++++++++++++++---------------
1 file changed, 17 insertions(+), 17 deletions(-)
diff --git a/arch/powerpc/platforms/powernv/vas-window.c b/arch/powerpc/platforms/powernv/vas-window.c
index 67ffc5d..8ab8a82 100644
--- a/arch/powerpc/platforms/powernv/vas-window.c
+++ b/arch/powerpc/platforms/powernv/vas-window.c
@@ -1079,25 +1079,25 @@ static void poll_window_busy_state(struct vas_window *window)
}
}
+/*
+ * Have the hardware cast a window out of cache and wait for it to
+ * be completed.
+ *
+ * NOTE: It can take a relatively long time to cast the window context
+ * out of the cache. It is not strictly necessary to cast out if:
+ *
+ * - we clear the "Pin Window" bit (so hardware is free to evict)
+ *
+ * - we re-initialize the window context when it is reassigned.
+ *
+ * We do the former in vas_win_close() and latter in vas_win_open().
+ * So, ignoring the cast-out for now. We can add it as needed. If
+ * casting out becomes necessary we should consider offloading the
+ * job to a worker thread, so the window close can proceed quickly.
+ */
static void poll_window_castout(struct vas_window *window)
{
- int cached;
- u64 val;
-
- /* Cast window context out of the cache */
-retry:
- val = read_hvwc_reg(window, VREG(WIN_CTX_CACHING_CTL));
- cached = GET_FIELD(VAS_WIN_CACHE_STATUS, val);
- if (cached) {
- val = 0ULL;
- val = SET_FIELD(VAS_CASTOUT_REQ, val, 1);
- val = SET_FIELD(VAS_PUSH_TO_MEM, val, 0);
- write_hvwc_reg(window, VREG(WIN_CTX_CACHING_CTL), val);
-
- set_current_state(TASK_UNINTERRUPTIBLE);
- schedule_timeout(HZ);
- goto retry;
- }
+ /* stub for now */
}
/*
--
2.7.4
next prev parent reply other threads:[~2017-11-08 2:24 UTC|newest]
Thread overview: 23+ messages / expand[flat|nested] mbox.gz Atom feed top
2017-11-08 2:23 [PATCH v3 00/18] powerpc/vas: Add support for FTW Sukadev Bhattiprolu
2017-11-08 2:23 ` [PATCH v3 01/18] powerpc/vas: init missing fields from [rt]xattr Sukadev Bhattiprolu
2017-11-14 11:12 ` [v3,01/18] " Michael Ellerman
2017-11-08 2:23 ` [PATCH v3 02/18] powerpc/vas: Validate window credits Sukadev Bhattiprolu
2017-11-08 2:23 ` [PATCH v3 03/18] powerpc/vas: Cleanup some debug code Sukadev Bhattiprolu
2017-11-08 2:23 ` Sukadev Bhattiprolu [this message]
2017-11-08 2:23 ` [PATCH v3 05/18] powerpc/vas: Use helper to unpin/close window Sukadev Bhattiprolu
2017-11-08 2:23 ` [PATCH v3 06/18] powerpc/vas: Reduce polling interval for busy state Sukadev Bhattiprolu
2017-11-08 2:23 ` [PATCH v3 07/18] powerpc/vas: Save configured window credits Sukadev Bhattiprolu
2017-11-08 2:23 ` [PATCH v3 08/18] powerpc/vas: poll for return of " Sukadev Bhattiprolu
2017-11-08 2:23 ` [PATCH v3 09/18] powerpc/vas: Create cpu to vas id mapping Sukadev Bhattiprolu
2017-11-08 2:23 ` [PATCH v3 10/18] powerpc/vas, nx-842: Define and use chip_to_vas_id() Sukadev Bhattiprolu
2017-11-20 17:57 ` Josh Boyer
2017-11-22 11:56 ` Michael Ellerman
2017-11-08 2:23 ` [PATCH v3 11/18] powerpc/vas: Export HVWC to debugfs Sukadev Bhattiprolu
2017-11-08 2:23 ` [PATCH v3 12/18] powerpc: have copy depend on CONFIG_BOOK3S_64 Sukadev Bhattiprolu
2017-11-08 2:23 ` [PATCH v3 13/18] powerpc: Add support for setting SPRN_TIDR Sukadev Bhattiprolu
2017-11-09 11:53 ` Michael Ellerman
2017-11-08 2:23 ` [PATCH v3 14/18] powerpc: Define set_thread_uses_vas() Sukadev Bhattiprolu
2017-11-08 2:23 ` [PATCH v3 15/18] powerpc: Emulate paste instruction Sukadev Bhattiprolu
2017-11-08 2:23 ` [PATCH v3 16/18] powerpc/vas: Define vas_win_paste_addr() Sukadev Bhattiprolu
2017-11-08 2:23 ` [PATCH v3 17/18] powerpc/vas: Define vas_win_id() Sukadev Bhattiprolu
2017-11-08 2:23 ` [PATCH v3 18/18] powerpc/vas: Add support for user receive window Sukadev Bhattiprolu
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