From: Ming Lei <ming.lei@redhat.com>
To: James Bottomley <James.Bottomley@HansenPartnership.com>,
linux-scsi@vger.kernel.org,
"Martin K . Petersen" <martin.petersen@oracle.com>,
linux-block@vger.kernel.org, Jens Axboe <axboe@kernel.dk>
Cc: Ming Lei <ming.lei@redhat.com>, Omar Sandoval <osandov@fb.com>,
Sathya Prakash <sathya.prakash@broadcom.com>,
Chaitra P B <chaitra.basappa@broadcom.com>,
Suganath Prabu Subramani <suganath-prabu.subramani@broadcom.com>,
Kashyap Desai <kashyap.desai@broadcom.com>,
Sumit Saxena <sumit.saxena@broadcom.com>,
Shivasharan S <shivasharan.srikanteshwara@broadcom.com>,
"Ewan D . Milne" <emilne@redhat.com>,
Hannes Reinecke <hare@suse.de>,
Bart Van Assche <bart.vanassche@wdc.com>
Subject: [PATCH 06/10] sbitmap: add helper of sbitmap_calculate_shift
Date: Tue, 11 Feb 2020 20:11:31 +0800 [thread overview]
Message-ID: <20200211121135.30064-7-ming.lei@redhat.com> (raw)
In-Reply-To: <20200211121135.30064-1-ming.lei@redhat.com>
Move code for calculating default shift into one public helper,
which can be used for SCSI to calculate shift.
Cc: Omar Sandoval <osandov@fb.com>
Cc: Sathya Prakash <sathya.prakash@broadcom.com>
Cc: Chaitra P B <chaitra.basappa@broadcom.com>
Cc: Suganath Prabu Subramani <suganath-prabu.subramani@broadcom.com>
Cc: Kashyap Desai <kashyap.desai@broadcom.com>
Cc: Sumit Saxena <sumit.saxena@broadcom.com>
Cc: Shivasharan S <shivasharan.srikanteshwara@broadcom.com>
Cc: Ewan D. Milne <emilne@redhat.com>
Cc: Hannes Reinecke <hare@suse.de>
Cc: Bart Van Assche <bart.vanassche@wdc.com>
Signed-off-by: Ming Lei <ming.lei@redhat.com>
---
include/linux/sbitmap.h | 18 ++++++++++++++++++
lib/sbitmap.c | 16 +++-------------
2 files changed, 21 insertions(+), 13 deletions(-)
diff --git a/include/linux/sbitmap.h b/include/linux/sbitmap.h
index 34343ce3ef6c..2a40364d6d00 100644
--- a/include/linux/sbitmap.h
+++ b/include/linux/sbitmap.h
@@ -337,6 +337,24 @@ static inline int sbitmap_test_bit(struct sbitmap *sb, unsigned int bitnr)
return test_bit(SB_NR_TO_BIT(sb, bitnr), __sbitmap_word(sb, bitnr));
}
+static inline int sbitmap_calculate_shift(unsigned int depth)
+{
+ int shift = ilog2(BITS_PER_LONG);
+
+ /*
+ * If the bitmap is small, shrink the number of bits per word so
+ * we spread over a few cachelines, at least. If less than 4
+ * bits, just forget about it, it's not going to work optimally
+ * anyway.
+ */
+ if (depth >= 4) {
+ while ((4U << shift) > depth)
+ shift--;
+ }
+
+ return shift;
+}
+
/**
* sbitmap_show() - Dump &struct sbitmap information to a &struct seq_file.
* @sb: Bitmap to show.
diff --git a/lib/sbitmap.c b/lib/sbitmap.c
index 254475865b3d..bb88a3643d64 100644
--- a/lib/sbitmap.c
+++ b/lib/sbitmap.c
@@ -96,19 +96,9 @@ int sbitmap_init_node(struct sbitmap *sb, unsigned int depth, int shift,
unsigned int bits_per_word;
unsigned int i;
- if (shift < 0) {
- shift = ilog2(BITS_PER_LONG);
- /*
- * If the bitmap is small, shrink the number of bits per word so
- * we spread over a few cachelines, at least. If less than 4
- * bits, just forget about it, it's not going to work optimally
- * anyway.
- */
- if (depth >= 4) {
- while ((4U << shift) > depth)
- shift--;
- }
- }
+ if (shift < 0)
+ shift = sbitmap_calculate_shift(depth);
+
bits_per_word = 1U << shift;
if (bits_per_word > BITS_PER_LONG)
return -EINVAL;
--
2.20.1
next prev parent reply other threads:[~2020-02-11 12:12 UTC|newest]
Thread overview: 15+ messages / expand[flat|nested] mbox.gz Atom feed top
2020-02-11 12:11 [PATCH 00/10] scsi: tracking device queue depth via sbitmap Ming Lei
2020-02-11 12:11 ` [PATCH 01/10] sbitmap: maintain allocation round_robin in sbitmap Ming Lei
2020-04-14 6:04 ` Hannes Reinecke
2020-02-11 12:11 ` [PATCH 02/10] sbitmap: add helpers for updating allocation hint Ming Lei
2020-04-14 6:05 ` Hannes Reinecke
2020-02-11 12:11 ` [PATCH 03/10] sbitmap: remove sbitmap_clear_bit_unlock Ming Lei
2020-04-14 6:06 ` Hannes Reinecke
2020-02-11 12:11 ` [PATCH 04/10] sbitmap: move allocation hint into sbitmap Ming Lei
2020-02-11 12:11 ` [PATCH 05/10] sbitmap: export sbitmap_weight Ming Lei
2020-02-11 12:11 ` Ming Lei [this message]
2020-02-11 12:11 ` [PATCH 07/10] blk-mq: return budget token from .get_budget callback Ming Lei
2020-02-11 12:11 ` [PATCH 08/10] blk-mq: pass budget token to dirver via blk_mq_queue_data Ming Lei
2020-02-11 12:11 ` [PATCH 09/10] scsi: add scsi_device_busy() to read sdev->device_busy Ming Lei
2020-02-11 12:11 ` [PATCH 10/10] scsi: replace sdev->device_busy with sbitmap Ming Lei
[not found] ` <202002140428.063yIjwM%lkp@intel.com>
2020-02-14 9:16 ` Ming Lei
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